Handle the DSC pixel throughput quirk, limiting the compressed link-bpp
value for Synaptics Panamera branch devices, working around a
blank/unstable output issue observed on docking stations containing
these branch devices, when using a mode with a high pixel clock and a
high compressed link-bpp value.
For now use the same mode clock limit for RGB/YUV444 and YUV422/420
output modes. This may result in limiting the link-bpp value for a
YUV422/420 output mode already at a lower than required mode clock.
Reported-by: Vidya Srinivas <vidya.srini...@intel.com>
Reported-by: Swati Sharma <swati2.sha...@intel.com>
Signed-off-by: Imre Deak <imre.d...@intel.com>
---
.../drm/i915/display/intel_display_types.h | 1 +
drivers/gpu/drm/i915/display/intel_dp.c | 57 +++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
b/drivers/gpu/drm/i915/display/intel_display_types.h
index 73bdafae604f8..aff63bf0f2294 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -551,6 +551,7 @@ struct intel_connector {
u8 fec_capability;
u8 dsc_hblank_expansion_quirk:1;
+ u8 dsc_throughput_quirk:1;
u8 dsc_decompression_enabled:1;
struct {
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index dd082d2fcc968..7cc9364f9af88 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2509,6 +2509,56 @@ int intel_dp_dsc_compute_config(struct intel_dp
*intel_dp,
return 0;
}
+static void
+adjust_limits_for_dsc_throughput_quirk(const struct intel_connector *connector,
+ const struct intel_crtc_state
*crtc_state,
+ struct link_config_limits *limits)
+{
+ struct intel_display *display = to_intel_display(connector);
+ const struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+ const struct drm_display_mode *adjusted_mode =
+ &crtc_state->hw.adjusted_mode;
+ int max_bpp_x16;
+
+ if (!connector->dp.dsc_throughput_quirk)
+ return;
+
+ /*
+ * Synaptics Panamera branch devices have a problem decompressing a
+ * stream with a compressed link-bpp higher than 12, if the pixel
+ * clock is higher than ~50 % of the maximum overall throughput
+ * reported by the branch device. Work around this by limiting the
+ * maximum link bpp for such pixel clocks.
+ *
+ * TODO: Use the throughput value specific to the actual RGB/YUV
+ * format of the output, after determining the pixel clock limit for
+ * YUV modes. For now use the smaller of the throughput values, which
+ * may result in limiting the link-bpp value already at a lower than
+ * required mode clock in case of native YUV422/420 output formats.
+ * The RGB/YUV444 throughput value should be always either equal or
+ * smaller than the YUV422/420 value, but let's not depend on this
+ * assumption.
+ */
+ if (adjusted_mode->crtc_clock <
+ min(connector->dp.dsc_branch_caps.overall_throughput.rgb_yuv444,
+ connector->dp.dsc_branch_caps.overall_throughput.yuv422_420) /
2)
+ return;
+
+ max_bpp_x16 = clamp(fxp_q4_from_int(12),
+ limits->link.min_bpp_x16, limits->link.max_bpp_x16);
+
+ if (max_bpp_x16 >= limits->link.max_bpp_x16)
+ return;
+
+ drm_dbg_kms(display->drm,
+ "[CRTC:%d:%s][CONNECTOR:%d:%s] Decreasing link max bpp to "
FXP_Q4_FMT " due to DSC throughput quirk\n",
+ crtc->base.base.id, crtc->base.name,
+ connector->base.base.id, connector->base.name,
+ FXP_Q4_ARGS(max_bpp_x16));
+
+ limits->link.max_bpp_x16 = max_bpp_x16;
+}
+
/*
* Calculate the output link min, max bpp values in limits based on the pipe
bpp
* range, crtc_state and dsc mode. Return true on success.
@@ -2558,6 +2608,8 @@ intel_dp_compute_config_link_bpp_limits(struct intel_dp
*intel_dp,
limits->link.max_bpp_x16 = max_link_bpp_x16;
+ adjust_limits_for_dsc_throughput_quirk(connector, crtc_state, limits);
+
drm_dbg_kms(display->drm,
"[ENCODER:%d:%s][CRTC:%d:%s] DP link limits: pixel clock %d
kHz DSC %s max lanes %d max rate %d max pipe_bpp %d max link_bpp " FXP_Q4_FMT
"\n",
encoder->base.base.id, encoder->base.name,
@@ -4272,6 +4324,7 @@ void intel_dp_get_dsc_sink_cap(u8 dpcd_rev,
connector->dp.fec_capability = 0;
memset(&connector->dp.dsc_branch_caps, 0,
sizeof(connector->dp.dsc_branch_caps));
+ connector->dp.dsc_throughput_quirk = false;
if (dpcd_rev < DP_DPCD_REV_14)
return;
@@ -4292,6 +4345,10 @@ void intel_dp_get_dsc_sink_cap(u8 dpcd_rev,
return;
init_dsc_overall_throughput_limits(connector, is_branch);
+
+ if (drm_dp_has_quirk(desc, DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT) &&
+ desc->ident.hw_rev == 0x10)
+ connector->dp.dsc_throughput_quirk = true;
}
static void intel_edp_get_dsc_sink_cap(u8 edp_dpcd_rev, struct intel_connector
*connector)
--
2.49.1
