4.19-stable review patch. If anyone has any objections, please let me know.
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From: Nicholas Kazlauskas nicholas.kazlauskas@amd.com
commit 49f1c44b581b08e3289127ffe58bd208c3166701 upstream.
[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")
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 ++ 1 file changed, 2 insertions(+)
--- 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(str 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_sta if (new_state) { __drm_atomic_helper_connector_duplicate_state(connector, &new_state->base); + new_state->max_bpc = state->max_bpc; return &new_state->base; }