Some Synaptics MST 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 throughput capability reported by the branch
device. The screen remains blank, or for some - mostly black content -
gets enabled, but may stil have jitter artifacts.
At least the following docking stations are affected, based on testing
both with any Intel devices or the UCD-500 reference device as a source:
- DELL WD19DCS, DELL WD19TB3, DELL WD22TB4
- ThinkPad 40AN
- HP G2
At least the following docking stations are free from this problem,
based on tests with a source/sink/mode etc. configuration matching the
test cases used above:
- DELL Dual Charge HD22Q, DELL WD25TB5
- ThinkPad 40B0
- Anker 565
All the affected devices have an older version of the Synaptics MST
branch device (Panarema), whereas all the non-affected docking stations
have a newer branch device (at least Synaptics Panarema with a higher HW
revision number and Synaptics Cayenne models). Add the required quirk
entries accordingly. The quirk will be handled by the i915/xe drivers in
a follow-up change.
The latest firmware version of the Synaptics branch device for all the
affected devices tested above is 5.7 (as reported at DPCD address
0x50a/0x50b). For the DELL devices this corresponds to the latest
01.00.14.01.A03 firmware package version of the docking station.
v2:
- Document the DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT enum.
- Describe the quirk in more detail in the dpcd_quirk_list.
Cc: dri-de...@lists.freedesktop.org
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>
---
drivers/gpu/drm/display/drm_dp_helper.c | 4 ++++
include/drm/display/drm_dp_helper.h | 9 +++++++++
2 files changed, 13 insertions(+)
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 5426db21e53f..1c74fe9459ad 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2551,6 +2551,10 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
{ OUI(0x00, 0x0C, 0xE7), DEVICE_ID_ANY, false,
BIT(DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC) },
/* Apple MacBookPro 2017 15 inch eDP Retina panel reports too low
DP_MAX_LINK_RATE */
{ OUI(0x00, 0x10, 0xfa), DEVICE_ID(101, 68, 21, 101, 98, 97), false,
BIT(DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS) },
+ /* Synaptics Panamera supports only a compressed bpp of 12 above 50% of
its max DSC pixel throughput */
+ { OUI(0x90, 0xCC, 0x24), DEVICE_ID('S', 'Y', 'N', 'A', 0x53, 0x22),
true, BIT(DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT) },
+ { OUI(0x90, 0xCC, 0x24), DEVICE_ID('S', 'Y', 'N', 'A', 0x53, 0x31),
true, BIT(DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT) },
+ { OUI(0x90, 0xCC, 0x24), DEVICE_ID('S', 'Y', 'N', 'A', 0x53, 0x33),
true, BIT(DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT) },
};
#undef OUI
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index 52ce28097015..e438c4440995 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -828,6 +828,15 @@ enum drm_dp_quirk {
* requires enabling DSC.
*/
DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC,
+ /**
+ * @DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT:
+ *
+ * The device doesn't support DSC decompression at the maximum DSC
+ * pixel throughput and compressed bpp it indicates via its DPCD DSC
+ * capabilities. The compressed bpp must be limited above a device
+ * specific DSC pixel throughput.
+ */
+ DP_DPCD_QUIRK_DSC_THROUGHPUT_BPP_LIMIT,
};
/**
--
2.49.1
