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mmc: if possible, poll the busy state using DAT0

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Using the DAT0 line as a rdy/busy line is an alternative to reading the
status register of the card. It especially useful in situation where the
bus is not in a good shape, like when modes are switched.
This is also how the linux driver behaves.

Note of warning: As per the specification, while polling on DAT0 the CLK
must not turned off: "[...] Without a clock edge the Device (unless
previously disconnected by a deselect command (CMD7)) will force the DAT0
line down, forever. [...]"

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
This commit is contained in:
Jean-Jacques Hiblot 2019-07-02 10:53:53 +02:00 committed by Peng Fan
parent 863d10044a
commit cd0b80ec9c
3 changed files with 4 additions and 6 deletions
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2
drivers/mmc/mmc-uclass.c
View File

@ -47,7 +47,6 @@ int mmc_set_ios(struct mmc *mmc)
return dm_mmc_set_ios(mmc->dev);
}
#if CONFIG_IS_ENABLED(MMC_UHS_SUPPORT)
int dm_mmc_wait_dat0(struct udevice *dev, int state, int timeout)
{
struct dm_mmc_ops *ops = mmc_get_ops(dev);
@ -61,7 +60,6 @@ int mmc_wait_dat0(struct mmc *mmc, int state, int timeout)
{
return dm_mmc_wait_dat0(mmc->dev, state, timeout);
}
#endif
int dm_mmc_get_wp(struct udevice *dev)
{

6
drivers/mmc/mmc.c
View File

@ -29,12 +29,10 @@ static int mmc_select_mode_and_width(struct mmc *mmc, uint card_caps);
#if !CONFIG_IS_ENABLED(DM_MMC)
#if CONFIG_IS_ENABLED(MMC_UHS_SUPPORT)
static int mmc_wait_dat0(struct mmc *mmc, int state, int timeout)
{
return -ENOSYS;
}
#endif
__weak int board_mmc_getwp(struct mmc *mmc)
{
@ -233,6 +231,10 @@ int mmc_poll_for_busy(struct mmc *mmc, int timeout)
unsigned int status;
int err;
err = mmc_wait_dat0(mmc, 1, timeout);
if (err != -ENOSYS)
return err;
while (1) {
err = mmc_send_status(mmc, &status);
if (err)

2
include/mmc.h
View File

@ -445,7 +445,6 @@ struct dm_mmc_ops {
int (*execute_tuning)(struct udevice *dev, uint opcode);
#endif
#if CONFIG_IS_ENABLED(MMC_UHS_SUPPORT)
/**
* wait_dat0() - wait until dat0 is in the target state
* (CLK must be running during the wait)
@ -456,7 +455,6 @@ struct dm_mmc_ops {
* @return 0 if dat0 is in the target state, -ve on error
*/
int (*wait_dat0)(struct udevice *dev, int state, int timeout);
#endif
};
#define mmc_get_ops(dev) ((struct dm_mmc_ops *)(dev)->driver->ops)