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drm: DisplayPort AUX framework for v3.15-rc1
This series of patches implements a small framework that abstracts away some of the functionality that the DisplayPort AUX channel provides. It comes with a set of generic helpers that use the driver implementations to reduce code duplication. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAABAgAGBQJTDhU1AAoJEN0jrNd/PrOh5OoP/1tmkV0cgcMp//M2i0hWptvU ifO1SdwsnSMKajM8ytJuW+1e7UBStQg3QzpEwaTcvOuKHqE2WtDksh7yYUaj5Tv/ SB7n0cS6rxbdIQ9SCFDVHT+A9N/YUeCj8l9BxgabaNnguA4I8Dydp9cfm3fCq835 cWGf02TXw2H6V5mbNjaBggWSp4iqG/6+QxAn07o+u137kbTlRMO6pBjEflaVBCDP rYIJ5q2UgN//wI4e+ESYEyU8Cze5Zaevk+/L4Qg9FNbzGSjeEmfVNLuPdLkZOYV6 6RSwOgSlZWGjMRsIWHta2u0VDQB/Wr0PjDqx4mWcYyrFJfms5yrc6R4JmQwGRFxi ucSkL9Ak1LKK2NLhrfnzL1ogHkU/5EEPV1dDxK7P0Milzg2YUDwhv1zn+ssmtUuQ zZrPYJNsG/rdNfA7BeGBpqjLnL93YWQXNbeIx2m/yQIT4YA63jkKgqz5p9NOvkjp ++JdGX0By1iOMG9SOOFVIOLorohVnYDqrp+klsIuXVJhw3/bvPLcXejRNPuODRoQ aw/8nLwHubDvG2lJVgVFmrlofxcfeIbYsf0AE2wiATRjjZ37+YfCdFOpu2E0cMN1 mLquAHkpTupYr0SfKW1ofhJuxDcvkir7ud9zpqKRxfUh0xFmnCaaDh48FocWpdSG MsPdMJ0g01uzzxlkFqKk =SovB -----END PGP SIGNATURE----- Merge tag 'drm/dp-aux-for-3.15-rc1' of git://anongit.freedesktop.org/tegra/linux into drm-next drm: DisplayPort AUX framework for v3.15-rc1 This series of patches implements a small framework that abstracts away some of the functionality that the DisplayPort AUX channel provides. It comes with a set of generic helpers that use the driver implementations to reduce code duplication. * tag 'drm/dp-aux-for-3.15-rc1' of git://anongit.freedesktop.org/tegra/linux: drm/dp: Allow registering AUX channels as I2C busses drm/dp: Add DisplayPort link helpers drm/dp: Add drm_dp_dpcd_read_link_status() drm/dp: Add AUX channel infrastructure
This commit is contained in:
Dave Airlie
commit
6ba6b7cdaf
@ -346,3 +346,398 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
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}
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}
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EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
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/**
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* DOC: dp helpers
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*
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* The DisplayPort AUX channel is an abstraction to allow generic, driver-
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* independent access to AUX functionality. Drivers can take advantage of
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* this by filling in the fields of the drm_dp_aux structure.
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*
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* Transactions are described using a hardware-independent drm_dp_aux_msg
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* structure, which is passed into a driver's .transfer() implementation.
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* Both native and I2C-over-AUX transactions are supported.
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*/
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static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
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unsigned int offset, void *buffer, size_t size)
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{
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struct drm_dp_aux_msg msg;
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unsigned int retry;
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int err;
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memset(&msg, 0, sizeof(msg));
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msg.address = offset;
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msg.request = request;
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msg.buffer = buffer;
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msg.size = size;
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/*
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* The specification doesn't give any recommendation on how often to
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* retry native transactions, so retry 7 times like for I2C-over-AUX
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* transactions.
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*/
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for (retry = 0; retry < 7; retry++) {
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err = aux->transfer(aux, &msg);
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if (err < 0) {
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if (err == -EBUSY)
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continue;
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return err;
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}
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if (err < size)
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return -EPROTO;
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switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
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case DP_AUX_NATIVE_REPLY_ACK:
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return err;
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case DP_AUX_NATIVE_REPLY_NACK:
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return -EIO;
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case DP_AUX_NATIVE_REPLY_DEFER:
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usleep_range(400, 500);
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break;
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}
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}
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DRM_ERROR("too many retries, giving up\n");
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return -EIO;
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}
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/**
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* drm_dp_dpcd_read() - read a series of bytes from the DPCD
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* @aux: DisplayPort AUX channel
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* @offset: address of the (first) register to read
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* @buffer: buffer to store the register values
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* @size: number of bytes in @buffer
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*
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* Returns the number of bytes transferred on success, or a negative error
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* code on failure. -EIO is returned if the request was NAKed by the sink or
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* if the retry count was exceeded. If not all bytes were transferred, this
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* function returns -EPROTO. Errors from the underlying AUX channel transfer
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* function, with the exception of -EBUSY (which causes the transaction to
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* be retried), are propagated to the caller.
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*/
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ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
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void *buffer, size_t size)
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{
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return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
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size);
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}
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EXPORT_SYMBOL(drm_dp_dpcd_read);
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/**
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* drm_dp_dpcd_write() - write a series of bytes to the DPCD
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* @aux: DisplayPort AUX channel
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* @offset: address of the (first) register to write
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* @buffer: buffer containing the values to write
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* @size: number of bytes in @buffer
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*
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* Returns the number of bytes transferred on success, or a negative error
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* code on failure. -EIO is returned if the request was NAKed by the sink or
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* if the retry count was exceeded. If not all bytes were transferred, this
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* function returns -EPROTO. Errors from the underlying AUX channel transfer
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* function, with the exception of -EBUSY (which causes the transaction to
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* be retried), are propagated to the caller.
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*/
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ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
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void *buffer, size_t size)
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{
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return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
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size);
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}
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EXPORT_SYMBOL(drm_dp_dpcd_write);
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/**
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* drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
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* @aux: DisplayPort AUX channel
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* @status: buffer to store the link status in (must be at least 6 bytes)
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*
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* Returns the number of bytes transferred on success or a negative error
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* code on failure.
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*/
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int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
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u8 status[DP_LINK_STATUS_SIZE])
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{
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return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
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DP_LINK_STATUS_SIZE);
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}
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EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
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/**
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* drm_dp_link_probe() - probe a DisplayPort link for capabilities
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* @aux: DisplayPort AUX channel
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* @link: pointer to structure in which to return link capabilities
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*
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* The structure filled in by this function can usually be passed directly
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* into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
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* configure the link based on the link's capabilities.
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 values[3];
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int err;
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memset(link, 0, sizeof(*link));
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err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
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if (err < 0)
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return err;
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link->revision = values[0];
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link->rate = drm_dp_bw_code_to_link_rate(values[1]);
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link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
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if (values[2] & DP_ENHANCED_FRAME_CAP)
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link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING;
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return 0;
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}
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EXPORT_SYMBOL(drm_dp_link_probe);
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/**
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* drm_dp_link_power_up() - power up a DisplayPort link
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* @aux: DisplayPort AUX channel
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* @link: pointer to a structure containing the link configuration
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 value;
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int err;
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/* DP_SET_POWER register is only available on DPCD v1.1 and later */
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if (link->revision < 0x11)
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return 0;
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err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
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if (err < 0)
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return err;
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value &= ~DP_SET_POWER_MASK;
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value |= DP_SET_POWER_D0;
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err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
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if (err < 0)
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return err;
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/*
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* According to the DP 1.1 specification, a "Sink Device must exit the
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* power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
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* Control Field" (register 0x600).
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*/
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usleep_range(1000, 2000);
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return 0;
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}
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EXPORT_SYMBOL(drm_dp_link_power_up);
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/**
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* drm_dp_link_configure() - configure a DisplayPort link
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* @aux: DisplayPort AUX channel
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* @link: pointer to a structure containing the link configuration
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 values[2];
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int err;
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values[0] = drm_dp_link_rate_to_bw_code(link->rate);
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values[1] = link->num_lanes;
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if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING)
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values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
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err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
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if (err < 0)
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return err;
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return 0;
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}
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EXPORT_SYMBOL(drm_dp_link_configure);
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/*
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* I2C-over-AUX implementation
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*/
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static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
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I2C_FUNC_SMBUS_READ_BLOCK_DATA |
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I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
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I2C_FUNC_10BIT_ADDR;
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}
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/*
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* Transfer a single I2C-over-AUX message and handle various error conditions,
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* retrying the transaction as appropriate.
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*/
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static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
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{
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unsigned int retry;
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int err;
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/*
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* DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
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* is required to retry at least seven times upon receiving AUX_DEFER
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* before giving up the AUX transaction.
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*/
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for (retry = 0; retry < 7; retry++) {
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err = aux->transfer(aux, msg);
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if (err < 0) {
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if (err == -EBUSY)
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continue;
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DRM_DEBUG_KMS("transaction failed: %d\n", err);
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return err;
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}
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if (err < msg->size)
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return -EPROTO;
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switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
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case DP_AUX_NATIVE_REPLY_ACK:
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/*
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* For I2C-over-AUX transactions this isn't enough, we
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* need to check for the I2C ACK reply.
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*/
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break;
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case DP_AUX_NATIVE_REPLY_NACK:
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DRM_DEBUG_KMS("native nack\n");
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return -EREMOTEIO;
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case DP_AUX_NATIVE_REPLY_DEFER:
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DRM_DEBUG_KMS("native defer");
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/*
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* We could check for I2C bit rate capabilities and if
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* available adjust this interval. We could also be
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* more careful with DP-to-legacy adapters where a
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* long legacy cable may force very low I2C bit rates.
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*
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* For now just defer for long enough to hopefully be
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* safe for all use-cases.
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*/
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usleep_range(500, 600);
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continue;
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default:
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DRM_ERROR("invalid native reply %#04x\n", msg->reply);
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return -EREMOTEIO;
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}
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switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
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case DP_AUX_I2C_REPLY_ACK:
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/*
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* Both native ACK and I2C ACK replies received. We
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* can assume the transfer was successful.
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*/
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return 0;
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case DP_AUX_I2C_REPLY_NACK:
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DRM_DEBUG_KMS("I2C nack\n");
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return -EREMOTEIO;
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case DP_AUX_I2C_REPLY_DEFER:
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DRM_DEBUG_KMS("I2C defer\n");
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usleep_range(400, 500);
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continue;
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default:
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DRM_ERROR("invalid I2C reply %#04x\n", msg->reply);
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return -EREMOTEIO;
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}
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}
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DRM_ERROR("too many retries, giving up\n");
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return -EREMOTEIO;
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}
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static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
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int num)
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{
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struct drm_dp_aux *aux = adapter->algo_data;
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unsigned int i, j;
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for (i = 0; i < num; i++) {
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struct drm_dp_aux_msg msg;
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int err;
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/*
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* Many hardware implementations support FIFOs larger than a
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* single byte, but it has been empirically determined that
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* transferring data in larger chunks can actually lead to
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* decreased performance. Therefore each message is simply
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* transferred byte-by-byte.
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*/
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for (j = 0; j < msgs[i].len; j++) {
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memset(&msg, 0, sizeof(msg));
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msg.address = msgs[i].addr;
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msg.request = (msgs[i].flags & I2C_M_RD) ?
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DP_AUX_I2C_READ :
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DP_AUX_I2C_WRITE;
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/*
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* All messages except the last one are middle-of-
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* transfer messages.
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*/
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if ((i < num - 1) || (j < msgs[i].len - 1))
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msg.request |= DP_AUX_I2C_MOT;
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msg.buffer = msgs[i].buf + j;
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msg.size = 1;
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err = drm_dp_i2c_do_msg(aux, &msg);
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if (err < 0)
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return err;
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}
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}
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return num;
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}
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static const struct i2c_algorithm drm_dp_i2c_algo = {
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.functionality = drm_dp_i2c_functionality,
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.master_xfer = drm_dp_i2c_xfer,
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};
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/**
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* drm_dp_aux_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
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* @aux: DisplayPort AUX channel
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux)
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{
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aux->ddc.algo = &drm_dp_i2c_algo;
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aux->ddc.algo_data = aux;
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aux->ddc.retries = 3;
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aux->ddc.class = I2C_CLASS_DDC;
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aux->ddc.owner = THIS_MODULE;
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aux->ddc.dev.parent = aux->dev;
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aux->ddc.dev.of_node = aux->dev->of_node;
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strncpy(aux->ddc.name, dev_name(aux->dev), sizeof(aux->ddc.name));
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return i2c_add_adapter(&aux->ddc);
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}
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EXPORT_SYMBOL(drm_dp_aux_register_i2c_bus);
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/**
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* drm_dp_aux_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
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* @aux: DisplayPort AUX channel
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*/
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void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux)
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{
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i2c_del_adapter(&aux->ddc);
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}
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EXPORT_SYMBOL(drm_dp_aux_unregister_i2c_bus);
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@ -291,6 +291,7 @@
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#define DP_SET_POWER 0x600
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# define DP_SET_POWER_D0 0x1
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# define DP_SET_POWER_D3 0x2
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# define DP_SET_POWER_MASK 0x3
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#define DP_PSR_ERROR_STATUS 0x2006 /* XXX 1.2? */
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# define DP_PSR_LINK_CRC_ERROR (1 << 0)
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@ -398,4 +399,114 @@ drm_dp_enhanced_frame_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
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(dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP);
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}
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/*
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* DisplayPort AUX channel
|
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*/
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||||
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/**
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* struct drm_dp_aux_msg - DisplayPort AUX channel transaction
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* @address: address of the (first) register to access
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* @request: contains the type of transaction (see DP_AUX_* macros)
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* @reply: upon completion, contains the reply type of the transaction
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* @buffer: pointer to a transmission or reception buffer
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* @size: size of @buffer
|
||||
*/
|
||||
struct drm_dp_aux_msg {
|
||||
unsigned int address;
|
||||
u8 request;
|
||||
u8 reply;
|
||||
void *buffer;
|
||||
size_t size;
|
||||
};
|
||||
|
||||
/**
|
||||
* struct drm_dp_aux - DisplayPort AUX channel
|
||||
* @ddc: I2C adapter that can be used for I2C-over-AUX communication
|
||||
* @dev: pointer to struct device that is the parent for this AUX channel
|
||||
* @transfer: transfers a message representing a single AUX transaction
|
||||
*
|
||||
* The .dev field should be set to a pointer to the device that implements
|
||||
* the AUX channel.
|
||||
*
|
||||
* Drivers provide a hardware-specific implementation of how transactions
|
||||
* are executed via the .transfer() function. A pointer to a drm_dp_aux_msg
|
||||
* structure describing the transaction is passed into this function. Upon
|
||||
* success, the implementation should return the number of payload bytes
|
||||
* that were transferred, or a negative error-code on failure. Helpers
|
||||
* propagate errors from the .transfer() function, with the exception of
|
||||
* the -EBUSY error, which causes a transaction to be retried. On a short,
|
||||
* helpers will return -EPROTO to make it simpler to check for failure.
|
||||
*
|
||||
* An AUX channel can also be used to transport I2C messages to a sink. A
|
||||
* typical application of that is to access an EDID that's present in the
|
||||
* sink device. The .transfer() function can also be used to execute such
|
||||
* transactions. The drm_dp_aux_register_i2c_bus() function registers an
|
||||
* I2C adapter that can be passed to drm_probe_ddc(). Upon removal, drivers
|
||||
* should call drm_dp_aux_unregister_i2c_bus() to remove the I2C adapter.
|
||||
*/
|
||||
struct drm_dp_aux {
|
||||
struct i2c_adapter ddc;
|
||||
struct device *dev;
|
||||
|
||||
ssize_t (*transfer)(struct drm_dp_aux *aux,
|
||||
struct drm_dp_aux_msg *msg);
|
||||
};
|
||||
|
||||
ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
|
||||
void *buffer, size_t size);
|
||||
ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
|
||||
void *buffer, size_t size);
|
||||
|
||||
/**
|
||||
* drm_dp_dpcd_readb() - read a single byte from the DPCD
|
||||
* @aux: DisplayPort AUX channel
|
||||
* @offset: address of the register to read
|
||||
* @valuep: location where the value of the register will be stored
|
||||
*
|
||||
* Returns the number of bytes transferred (1) on success, or a negative
|
||||
* error code on failure.
|
||||
*/
|
||||
static inline ssize_t drm_dp_dpcd_readb(struct drm_dp_aux *aux,
|
||||
unsigned int offset, u8 *valuep)
|
||||
{
|
||||
return drm_dp_dpcd_read(aux, offset, valuep, 1);
|
||||
}
|
||||
|
||||
/**
|
||||
* drm_dp_dpcd_writeb() - write a single byte to the DPCD
|
||||
* @aux: DisplayPort AUX channel
|
||||
* @offset: address of the register to write
|
||||
* @value: value to write to the register
|
||||
*
|
||||
* Returns the number of bytes transferred (1) on success, or a negative
|
||||
* error code on failure.
|
||||
*/
|
||||
static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
|
||||
unsigned int offset, u8 value)
|
||||
{
|
||||
return drm_dp_dpcd_write(aux, offset, &value, 1);
|
||||
}
|
||||
|
||||
int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
|
||||
u8 status[DP_LINK_STATUS_SIZE]);
|
||||
|
||||
/*
|
||||
* DisplayPort link
|
||||
*/
|
||||
#define DP_LINK_CAP_ENHANCED_FRAMING (1 << 0)
|
||||
|
||||
struct drm_dp_link {
|
||||
unsigned char revision;
|
||||
unsigned int rate;
|
||||
unsigned int num_lanes;
|
||||
unsigned long capabilities;
|
||||
};
|
||||
|
||||
int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);
|
||||
int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
|
||||
int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
|
||||
|
||||
int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux);
|
||||
void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux);
|
||||
|
||||
#endif /* _DRM_DP_HELPER_H_ */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user