[PATCH] SWDEV-476969 - dm/amdgpu: Fail dm_atomic_check if cursor overlay is required at MAX_SURFACES

[Mario Limonciello]

Although it's really useful information for AMD people, the Jira 
shouldn't be in the "title" of the commit message.

"If" we want to get into the habit of including this information for 
display code we should come up with a prescriptive field that goes into 
the commit message during promotion and it should be part of all patches 
in the promotion that have it.

Something like this:

AMD-Jira: SWDEV-476969

Probably need to align that with other stakeholders though before 
starting that way.

On 11/14/2024 08:37, Zaeem Mohamed wrote:
> [why]
> Prevent index-out-of-bounds due to requiring cursor overlay when
> plane_count is MAX_SURFACES.
> 
> [how]
> Bounds check on plane_count when requiring overlay cursor.
> 

Any link to failing bugs or anything like that you can include?

> Co-developed-by: Melissa Wen <mwen at igalia.com>
> Signed-off-by: Zaeem Mohamed <zaeem.mohamed at amd.com>

You're missing Melisaa's SoB for a co-developed patch.
IIRC this should fail checkpatch.

> ---
>   amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/amdgpu_dm/amdgpu_dm.c b/amdgpu_dm/amdgpu_dm.c
> index 97e0a1bbba..964497c613 100644
> --- a/amdgpu_dm/amdgpu_dm.c
> +++ b/amdgpu_dm/amdgpu_dm.c
> @@ -11821,8 +11821,16 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
>   
>   		/* Overlay cusor not subject to native cursor restrictions */
>   		dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
> -		if (dm_new_crtc_state->cursor_mode == DM_CURSOR_OVERLAY_MODE)
> +		if (dm_new_crtc_state->cursor_mode == DM_CURSOR_OVERLAY_MODE) {
> +			if (dc->current_state->stream_status->plane_count > MAX_SURFACES) {
> +				drm_dbg_driver(crtc->dev,
> +				       "Can't enable cursor plane with %d planes\n", MAX_SURFACES);
> +				ret = -EINVAL;
> +				goto fail;
> +			}
> +
>   			continue;
> +		}
>   
>   		/* Check if rotation or scaling is enabled on DCN401 */
>   		if ((drm_plane_mask(crtc->cursor) & new_crtc_state->plane_mask) &&