Attachment 142958 Details for Bug 109122 – possible fix

[patch] possible fix

0001-drm-amd-display-Fix-unintialized-max_bpc-state-value.patch (text/plain), 2.42 KB, created by Alex Deucher on 2019-01-03 15:47:05 UTC

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Creator: Alex Deucher

Created: 2019-01-03 15:47:05 UTC

Size: 2.42 KB

patch

obsolete

>From c65b6f51bc0b4cb2cf808d08c1c484d247b0b489 Mon Sep 17 00:00:00 2001
>From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
>Date: Wed, 28 Nov 2018 16:17:50 -0500
>Subject: [PATCH] drm/amd/display: Fix unintialized max_bpc state values
>
>[Why]
>If the "max bpc" isn't explicitly set in the atomic state then it
>have a value of 0. This has the correct behavior of limiting a panel
>to 8bpc in the case where the panel supports 8bpc. In the case of eDP
>panels this isn't a true assumption - there are panels that can only
>do 6bpc.
>
>Banding occurs for these displays.
>
>[How]
>Initialize the max_bpc when the connector resets to 8bpc. Also carry
>over the value when the state is duplicated.
>
>Bugzilla: https://bugs.freedesktop.org/108825
>Fixes: 307638884f72 ("drm/amd/display: Support amdgpu "max bpc" connector property")
>
>Fixes regression caused by the automatic patch select of these two patches:
>https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/gpu/drm/amd?h=linux-4.19.y&id=a0c25b4098b8de23f34f81860ddc3cbaaa159189
>https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/gpu/drm/amd?h=linux-4.19.y&id=3374518d4d1ae021dc60885f4ea8dca0a3ca290f
>Bug: https://bugs.freedesktop.org/show_bug.cgi?id=109122
>
>Cc: Sasha Levin <sashal@kernel.org>
>Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
>Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
>Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>(cherry picked from commit 49f1c44b581b08e3289127ffe58bd208c3166701)
>---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
>diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>index 299def84e69c..d792735f1365 100644
>--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>@@ -2894,6 +2894,7 @@ void amdgpu_dm_connector_funcs_reset(struct drm_connector *connector)
> 		state->underscan_enable = false;
> 		state->underscan_hborder = 0;
> 		state->underscan_vborder = 0;
>+		state->max_bpc = 8;
> 
> 		__drm_atomic_helper_connector_reset(connector, &state->base);
> 	}
>@@ -2911,6 +2912,7 @@ amdgpu_dm_connector_atomic_duplicate_state(struct drm_connector *connector)
> 	if (new_state) {
> 		__drm_atomic_helper_connector_duplicate_state(connector,
> 							      &new_state->base);
>+		new_state->max_bpc = state->max_bpc;
> 		return &new_state->base;
> 	}
> 
>-- 
>2.20.1
>

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