[PATCH] drm/amd/display: Always allocate initial connector state state

[Li, Sun peng (Leo)]

On 2019-06-04 3:21 p.m., Nicholas Kazlauskas wrote:
> [Why]
> Unlike our regular connectors, MST connectors don't start off with
> an initial connector state. This causes a NULL pointer dereference to
> occur when attaching the bpc property since it tries to modify the
> connector state.
> 
> We need an initial connector state on the connector to avoid the crash.
> 
> [How]
> Use our reset helper to allocate an initial state and reset the values
> to their defaults. We were already doing this before, just not for
> MST connectors.
> 
> Cc: Leo Li <sunpeng.li at amd.com>
> Cc: Roman Li <roman.li at amd.com>
> Cc: Harry Wentland <harry.wentland at amd.com>
> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>

LGTM,

Reviewed-by: Leo Li <sunpeng.li at amd.com>

> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> 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 a698c8f272ed..4523ab100bc3 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4743,6 +4743,13 @@ void amdgpu_dm_connector_init_helper(struct amdgpu_display_manager *dm,
>   {
>   	struct amdgpu_device *adev = dm->ddev->dev_private;
>   
> +	/*
> +	 * Some of the properties below require access to state, like bpc.
> +	 * Allocate some default initial connector state with our reset helper.
> +	 */
> +	if (aconnector->base.funcs->reset)
> +		aconnector->base.funcs->reset(&aconnector->base);
> +
>   	aconnector->connector_id = link_index;
>   	aconnector->dc_link = link;
>   	aconnector->base.interlace_allowed = false;
> @@ -4932,9 +4939,6 @@ static int amdgpu_dm_connector_init(struct amdgpu_display_manager *dm,
>   			&aconnector->base,
>   			&amdgpu_dm_connector_helper_funcs);
>   
> -	if (aconnector->base.funcs->reset)
> -		aconnector->base.funcs->reset(&aconnector->base);
> -
>   	amdgpu_dm_connector_init_helper(
>   		dm,
>   		aconnector,
>