Currently we seem to be using wrong DPCD register for reading compressed bpps,
reading min/max input bpc instead of compressed bpp.
Fix that, so that we now apply min/max compressed bpp limitations we get
from DP Spec Table 2-157 DP v2.0 and/or correspondent DPCD register
DP_DSC_MAX_BITS_PER_PIXEL_LOW/HIGH.
This might also allow us to get rid of an ugly compressed bpp recalculation,
which we had to add to make some MST hubs usable.
v2: - Fix operator precedence
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp_mst.c | 76 ++++++++++++++-------
1 file changed, 52 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index a88b852c437c..d987eee90064 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -174,6 +174,50 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
return 0;
}
+static u16 dsc_max_sink_compressed_bppx16(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
+ struct intel_crtc_state *pipe_config,
+ int bpc)
+{
+ u16 max_bppx16 = dsc_dpcd[DP_DSC_MAX_BITS_PER_PIXEL_LOW - DP_DSC_SUPPORT] |
+ ((dsc_dpcd[DP_DSC_MAX_BITS_PER_PIXEL_HI - DP_DSC_SUPPORT] &
+ DP_DSC_MAX_BITS_PER_PIXEL_HI_MASK) << DP_DSC_MAX_BITS_PER_PIXEL_HI_SHIFT);
+
+ if (max_bppx16)
+ return max_bppx16;
+ /*
+ * If support not given in DPCD 67h, 68h use the Maximum Allowed bit rate
+ * values as given in spec Table 2-157 DP v2.0
+ */
+ switch (pipe_config->output_format) {
+ case INTEL_OUTPUT_FORMAT_RGB:
+ case INTEL_OUTPUT_FORMAT_YCBCR444:
+ return bpc << 4;
+ case INTEL_OUTPUT_FORMAT_YCBCR420:
+ return (3 * (bpc / 2)) << 4;
+ default:
+ MISSING_CASE(pipe_config->output_format);
+ break;
+ }
+
+ return 0;
+}
+
+static u16 dsc_min_compressed_bppx16(struct intel_crtc_state *pipe_config)
+{
+ switch (pipe_config->output_format) {
+ case INTEL_OUTPUT_FORMAT_RGB:
+ case INTEL_OUTPUT_FORMAT_YCBCR444:
+ return 8 << 4;
+ case INTEL_OUTPUT_FORMAT_YCBCR420:
+ return 6 << 4;
+ default:
+ MISSING_CASE(pipe_config->output_format);
+ break;
+ }
+
+ return 0;
+}
+
static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
struct intel_crtc_state *crtc_state,
struct drm_connector_state *conn_state,
@@ -191,8 +235,6 @@ static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
u8 dsc_bpc[3] = {0};
int min_bpp, max_bpp, sink_min_bpp, sink_max_bpp;
u8 dsc_max_bpc;
- bool need_timeslot_recalc = false;
- u32 last_compressed_bpp;
/* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
if (DISPLAY_VER(i915) >= 12)
@@ -228,6 +270,14 @@ static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
if (max_bpp > sink_max_bpp)
max_bpp = sink_max_bpp;
+ /* Get Min/Max compressed bpp's for those Input Bpps we got for source/sink */
+ max_bpp = min(max_bpp, dsc_max_sink_compressed_bppx16(intel_dp->dsc_dpcd, crtc_state, max_bpp / 3) >> 4);
+ min_bpp = max(min_bpp, dsc_min_compressed_bppx16(crtc_state) >> 4);
+
+ /* Align compressed bpps according to our own constraints */
+ max_bpp = intel_dp_dsc_nearest_valid_bpp(i915, max_bpp, crtc_state->pipe_bpp);
+ min_bpp = intel_dp_dsc_nearest_valid_bpp(i915, min_bpp, crtc_state->pipe_bpp);
+
slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state, max_bpp,
min_bpp, limits,
conn_state, 2 * 3, true);
@@ -235,28 +285,6 @@ static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
if (slots < 0)
return slots;
- last_compressed_bpp = crtc_state->dsc.compressed_bpp;
-
- crtc_state->dsc.compressed_bpp = intel_dp_dsc_nearest_valid_bpp(i915,
- last_compressed_bpp,
- crtc_state->pipe_bpp);
-
- if (crtc_state->dsc.compressed_bpp != last_compressed_bpp)
- need_timeslot_recalc = true;
-
- /*
- * Apparently some MST hubs dislike if vcpi slots are not matching precisely
- * the actual compressed bpp we use.
- */
- if (need_timeslot_recalc) {
- slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state,
- crtc_state->dsc.compressed_bpp,
- crtc_state->dsc.compressed_bpp,
- limits, conn_state, 2 * 3, true);
- if (slots < 0)
- return slots;
- }
-
intel_link_compute_m_n(crtc_state->dsc.compressed_bpp,
crtc_state->lane_count,
adjusted_mode->crtc_clock,
--
2.37.3
