[PATCH] drm/amd/display: Fix unintialized max_bpc state values

[Wentland, Harry]

On 2018-11-29 10:44 a.m., Nicholas Kazlauskas wrote:
> [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 at amd.com>

Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry

> ---
>  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 ce00e56814ed..ede93d53e209 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3215,6 +3215,7 @@ 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);
>  	}
> @@ -3236,6 +3237,7 @@ amdgpu_dm_connector_atomic_duplicate_state(struct drm_connector *connector)
>  
>  	new_state->freesync_capable = state->freesync_capable;
>  	new_state->abm_level = state->abm_level;
> +	new_state->max_bpc = state->max_bpc;
>  
>  	return &new_state->base;
>  }
>