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drm/i915/dp: Fix dsc bpp calculations, v5.

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There was a integer wraparound when mode_clock became too high,
and we didn't correct for the FEC overhead factor when dividing,
with the calculations breaking at HBR3.

As a result our calculated bpp was way too high, and the link width
limitation never came into effect.

Print out the resulting bpp calcululations as a sanity check, just
in case we ever have to debug it later on again.

We also used the wrong factor for FEC. While bspec mentions 2.4%,
all the calculations use 1/0.972261, and the same ratio should be
applied to data M/N as well, so use it there when FEC is enabled.

This fixes the FIFO underrun we are seeing with FEC enabled.

Changes since v2:
- Handle fec_enable in intel_link_compute_m_n, so only data M/N is adjusted. (Ville)
- Fix initial hardware readout for FEC. (Ville)
Changes since v3:
- Remove bogus fec_to_mode_clock. (Ville)
Changes since v4:
- Use the correct register for icl. (Ville)
- Split hw readout to a separate patch.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: d9218c8f6c ("drm/i915/dp: Add helpers for Compressed BPP and Slice Count for DSC")
Cc: <stable@vger.kernel.org> # v5.0+
Cc: Manasi Navare <manasi.d.navare@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190925082110.17439-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
This commit is contained in:
Maarten Lankhorst 2019-09-25 10:21:09 +02:00
parent 1b8588741f
commit ed06efb801
5 changed files with 107 additions and 99 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/gpu/drm/i915/display/intel_display.c
View File

@ -7291,7 +7291,7 @@ retry:
pipe_config->fdi_lanes = lane;
intel_link_compute_m_n(pipe_config->pipe_bpp, lane, fdi_dotclock,
link_bw, &pipe_config->fdi_m_n, false);
link_bw, &pipe_config->fdi_m_n, false, false);
ret = ironlake_check_fdi_lanes(dev, intel_crtc->pipe, pipe_config);
if (ret == -EDEADLK)
@ -7538,11 +7538,15 @@ void
intel_link_compute_m_n(u16 bits_per_pixel, int nlanes,
int pixel_clock, int link_clock,
struct intel_link_m_n *m_n,
bool constant_n)
bool constant_n, bool fec_enable)
{
m_n->tu = 64;
u32 data_clock = bits_per_pixel * pixel_clock;
compute_m_n(bits_per_pixel * pixel_clock,
if (fec_enable)
data_clock = intel_dp_mode_to_fec_clock(data_clock);
m_n->tu = 64;
compute_m_n(data_clock,
link_clock * nlanes * 8,
&m_n->gmch_m, &m_n->gmch_n,
constant_n);

2
drivers/gpu/drm/i915/display/intel_display.h
View File

@ -443,7 +443,7 @@ enum phy_fia {
void intel_link_compute_m_n(u16 bpp, int nlanes,
int pixel_clock, int link_clock,
struct intel_link_m_n *m_n,
bool constant_n);
bool constant_n, bool fec_enable);
bool is_ccs_modifier(u64 modifier);
void lpt_disable_clkout_dp(struct drm_i915_private *dev_priv);
u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv,

184
drivers/gpu/drm/i915/display/intel_dp.c
View File

@ -76,8 +76,8 @@
#define DP_DSC_MAX_ENC_THROUGHPUT_0 340000
#define DP_DSC_MAX_ENC_THROUGHPUT_1 400000
/* DP DSC FEC Overhead factor = (100 - 2.4)/100 */
#define DP_DSC_FEC_OVERHEAD_FACTOR 976
/* DP DSC FEC Overhead factor = 1/(0.972261) */
#define DP_DSC_FEC_OVERHEAD_FACTOR 972261
/* Compliance test status bits */
#define INTEL_DP_RESOLUTION_SHIFT_MASK 0
@ -492,6 +492,97 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
return 0;
}
u32 intel_dp_mode_to_fec_clock(u32 mode_clock)
{
return div_u64(mul_u32_u32(mode_clock, 1000000U),
DP_DSC_FEC_OVERHEAD_FACTOR);
}
static u16 intel_dp_dsc_get_output_bpp(u32 link_clock, u32 lane_count,
u32 mode_clock, u32 mode_hdisplay)
{
u32 bits_per_pixel, max_bpp_small_joiner_ram;
int i;
/*
* Available Link Bandwidth(Kbits/sec) = (NumberOfLanes)*
* (LinkSymbolClock)* 8 * (TimeSlotsPerMTP)
* for SST -> TimeSlotsPerMTP is 1,
* for MST -> TimeSlotsPerMTP has to be calculated
*/
bits_per_pixel = (link_clock * lane_count * 8) /
intel_dp_mode_to_fec_clock(mode_clock);
DRM_DEBUG_KMS("Max link bpp: %u\n", bits_per_pixel);
/* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
max_bpp_small_joiner_ram = DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER / mode_hdisplay;
DRM_DEBUG_KMS("Max small joiner bpp: %u\n", max_bpp_small_joiner_ram);
/*
* Greatest allowed DSC BPP = MIN (output BPP from available Link BW
* check, output bpp from small joiner RAM check)
*/
bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
/* Error out if the max bpp is less than smallest allowed valid bpp */
if (bits_per_pixel < valid_dsc_bpp[0]) {
DRM_DEBUG_KMS("Unsupported BPP %u, min %u\n",
bits_per_pixel, valid_dsc_bpp[0]);
return 0;
}
/* Find the nearest match in the array of known BPPs from VESA */
for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp) - 1; i++) {
if (bits_per_pixel < valid_dsc_bpp[i + 1])
break;
}
bits_per_pixel = valid_dsc_bpp[i];
/*
* Compressed BPP in U6.4 format so multiply by 16, for Gen 11,
* fractional part is 0
*/
return bits_per_pixel << 4;
}
static u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
int mode_clock, int mode_hdisplay)
{
u8 min_slice_count, i;
int max_slice_width;
if (mode_clock <= DP_DSC_PEAK_PIXEL_RATE)
min_slice_count = DIV_ROUND_UP(mode_clock,
DP_DSC_MAX_ENC_THROUGHPUT_0);
else
min_slice_count = DIV_ROUND_UP(mode_clock,
DP_DSC_MAX_ENC_THROUGHPUT_1);
max_slice_width = drm_dp_dsc_sink_max_slice_width(intel_dp->dsc_dpcd);
if (max_slice_width < DP_DSC_MIN_SLICE_WIDTH_VALUE) {
DRM_DEBUG_KMS("Unsupported slice width %d by DP DSC Sink device\n",
max_slice_width);
return 0;
}
/* Also take into account max slice width */
min_slice_count = min_t(u8, min_slice_count,
DIV_ROUND_UP(mode_hdisplay,
max_slice_width));
/* Find the closest match to the valid slice count values */
for (i = 0; i < ARRAY_SIZE(valid_dsc_slicecount); i++) {
if (valid_dsc_slicecount[i] >
drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
false))
break;
if (min_slice_count <= valid_dsc_slicecount[i])
return valid_dsc_slicecount[i];
}
DRM_DEBUG_KMS("Unsupported Slice Count %d\n", min_slice_count);
return 0;
}
static enum drm_mode_status
intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
@ -2259,7 +2350,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
adjusted_mode->crtc_clock,
pipe_config->port_clock,
&pipe_config->dp_m_n,
constant_n);
constant_n, pipe_config->fec_enable);
if (intel_connector->panel.downclock_mode != NULL &&
dev_priv->drrs.type == SEAMLESS_DRRS_SUPPORT) {
@ -2269,7 +2360,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
intel_connector->panel.downclock_mode->clock,
pipe_config->port_clock,
&pipe_config->dp_m2_n2,
constant_n);
constant_n, pipe_config->fec_enable);
}
if (!HAS_DDI(dev_priv))
@ -4373,91 +4464,6 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
DP_DPRX_ESI_LEN;
}
u16 intel_dp_dsc_get_output_bpp(int link_clock, u8 lane_count,
int mode_clock, int mode_hdisplay)
{
u16 bits_per_pixel, max_bpp_small_joiner_ram;
int i;
/*
* Available Link Bandwidth(Kbits/sec) = (NumberOfLanes)*
* (LinkSymbolClock)* 8 * ((100-FECOverhead)/100)*(TimeSlotsPerMTP)
* FECOverhead = 2.4%, for SST -> TimeSlotsPerMTP is 1,
* for MST -> TimeSlotsPerMTP has to be calculated
*/
bits_per_pixel = (link_clock * lane_count * 8 *
DP_DSC_FEC_OVERHEAD_FACTOR) /
mode_clock;
/* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
max_bpp_small_joiner_ram = DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER /
mode_hdisplay;
/*
* Greatest allowed DSC BPP = MIN (output BPP from avaialble Link BW
* check, output bpp from small joiner RAM check)
*/
bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
/* Error out if the max bpp is less than smallest allowed valid bpp */
if (bits_per_pixel < valid_dsc_bpp[0]) {
DRM_DEBUG_KMS("Unsupported BPP %d\n", bits_per_pixel);
return 0;
}
/* Find the nearest match in the array of known BPPs from VESA */
for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp) - 1; i++) {
if (bits_per_pixel < valid_dsc_bpp[i + 1])
break;
}
bits_per_pixel = valid_dsc_bpp[i];
/*
* Compressed BPP in U6.4 format so multiply by 16, for Gen 11,
* fractional part is 0
*/
return bits_per_pixel << 4;
}
u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
int mode_clock,
int mode_hdisplay)
{
u8 min_slice_count, i;
int max_slice_width;
if (mode_clock <= DP_DSC_PEAK_PIXEL_RATE)
min_slice_count = DIV_ROUND_UP(mode_clock,
DP_DSC_MAX_ENC_THROUGHPUT_0);
else
min_slice_count = DIV_ROUND_UP(mode_clock,
DP_DSC_MAX_ENC_THROUGHPUT_1);
max_slice_width = drm_dp_dsc_sink_max_slice_width(intel_dp->dsc_dpcd);
if (max_slice_width < DP_DSC_MIN_SLICE_WIDTH_VALUE) {
DRM_DEBUG_KMS("Unsupported slice width %d by DP DSC Sink device\n",
max_slice_width);
return 0;
}
/* Also take into account max slice width */
min_slice_count = min_t(u8, min_slice_count,
DIV_ROUND_UP(mode_hdisplay,
max_slice_width));
/* Find the closest match to the valid slice count values */
for (i = 0; i < ARRAY_SIZE(valid_dsc_slicecount); i++) {
if (valid_dsc_slicecount[i] >
drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
false))
break;
if (min_slice_count <= valid_dsc_slicecount[i])
return valid_dsc_slicecount[i];
}
DRM_DEBUG_KMS("Unsupported Slice Count %d\n", min_slice_count);
return 0;
}
static void
intel_pixel_encoding_setup_vsc(struct intel_dp *intel_dp,
const struct intel_crtc_state *crtc_state)

6
drivers/gpu/drm/i915/display/intel_dp.h
View File

@ -103,10 +103,6 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp);
bool
intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status);
u16 intel_dp_dsc_get_output_bpp(int link_clock, u8 lane_count,
int mode_clock, int mode_hdisplay);
u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp, int mode_clock,
int mode_hdisplay);
bool intel_dp_read_dpcd(struct intel_dp *intel_dp);
bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp);
@ -119,4 +115,6 @@ static inline unsigned int intel_dp_unused_lane_mask(int lane_count)
return ~((1 << lane_count) - 1) & 0xf;
}
u32 intel_dp_mode_to_fec_clock(u32 mode_clock);
#endif /* __INTEL_DP_H__ */

2
drivers/gpu/drm/i915/display/intel_dp_mst.c
View File

@ -81,7 +81,7 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
adjusted_mode->crtc_clock,
crtc_state->port_clock,
&crtc_state->dp_m_n,
constant_n);
constant_n, crtc_state->fec_enable);
crtc_state->dp_m_n.tu = slots;
return 0;