This is a note to let you know that I've just added the patch titled
drm/amd/display: Allow DSC on supported MST branch devices
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-allow-dsc-on-supported-mst-branch-devices.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 94ebc035456a4ccacfbbef60c444079a256623ad Mon Sep 17 00:00:00 2001
From: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
Date: Fri, 12 Nov 2021 15:27:32 -0500
Subject: drm/amd/display: Allow DSC on supported MST branch devices
From: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
commit 94ebc035456a4ccacfbbef60c444079a256623ad upstream.
[Why]
When trying to lightup two 4k60 non-DSC displays behind a branch device
that supports DSC we can't lightup both at once due to bandwidth
limitations - each requires 48 VCPI slots but we only have 63.
[How]
The workaround already exists in the code but is guarded by a CONFIG
that cannot be set by the user and shouldn't need to be.
Check for specific branch device IDs to device whether to enable
the workaround for multiple display scenarios.
Reviewed-by: Hersen Wu <hersenxs.wu@xxxxxxx>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@xxxxxxx>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 20 +++++++++---
1 file changed, 16 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -36,6 +36,8 @@
#include "dm_helpers.h"
#include "dc_link_ddc.h"
+#include "ddc_service_types.h"
+#include "dpcd_defs.h"
#include "i2caux_interface.h"
#if defined(CONFIG_DEBUG_FS)
@@ -152,6 +154,16 @@ static const struct drm_connector_funcs
};
#if defined(CONFIG_DRM_AMD_DC_DCN)
+static bool needs_dsc_aux_workaround(struct dc_link *link)
+{
+ if (link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_90CC24 &&
+ (link->dpcd_caps.dpcd_rev.raw == DPCD_REV_14 || link->dpcd_caps.dpcd_rev.raw == DPCD_REV_12) &&
+ link->dpcd_caps.sink_count.bits.SINK_COUNT >= 2)
+ return true;
+
+ return false;
+}
+
static bool validate_dsc_caps_on_connector(struct amdgpu_dm_connector *aconnector)
{
struct dc_sink *dc_sink = aconnector->dc_sink;
@@ -159,7 +171,7 @@ static bool validate_dsc_caps_on_connect
u8 dsc_caps[16] = { 0 };
aconnector->dsc_aux = drm_dp_mst_dsc_aux_for_port(port);
-#if defined(CONFIG_HP_HOOK_WORKAROUND)
+
/*
* drm_dp_mst_dsc_aux_for_port() will return NULL for certain configs
* because it only check the dsc/fec caps of the "port variable" and not the dock
@@ -169,10 +181,10 @@ static bool validate_dsc_caps_on_connect
* Workaround: explicitly check the use case above and use the mst dock's aux as dsc_aux
*
*/
-
- if (!aconnector->dsc_aux && !port->parent->port_parent)
+ if (!aconnector->dsc_aux && !port->parent->port_parent &&
+ needs_dsc_aux_workaround(aconnector->dc_link))
aconnector->dsc_aux = &aconnector->mst_port->dm_dp_aux.aux;
-#endif
+
if (!aconnector->dsc_aux)
return false;
Patches currently in stable-queue which might be from nicholas.kazlauskas@xxxxxxx are
queue-5.10/drm-amd-display-allow-dsc-on-supported-mst-branch-devices.patch
