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drm/dp: Add quirk for Synaptics DSC throughput link-bpp limit

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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 (Panamera), whereas all the non-affected docking stations
have a newer branch device (at least Synaptics Panamera 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.
v3:
- s/Panarema/Panamera in the commit log.

Cc: dri-devel@lists.freedesktop.org
Reported-by: Vidya Srinivas <vidya.srinivas@intel.com>
Reported-and-tested-by: Swati Sharma <swati2.sharma@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250930182450.563016-2-imre.deak@intel.com
This commit is contained in:
Imre Deak 2025-09-30 21:24:45 +03:00
parent a5e07980e6
commit fcf6bddebf
2 changed files with 13 additions and 0 deletions
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4
drivers/gpu/drm/display/drm_dp_helper.c
View File

@ -2543,6 +2543,10 @@ 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

9
include/drm/display/drm_dp_helper.h
View File

@ -820,6 +820,15 @@ 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,
};
/**