Re: [PATCH v2 2/3] drm/vc4: hdmi: always cancel the scrambling work synchronously

["Maíra Canal" <mcanal@igalia.com>]

On 20/10/26 12:19, Lucas Tanure wrote:
> The scrambling work re-arms itself every second while a scrambled mode
> is active. When the output is disabled, the work may be executing at
> that moment rather than pending, and delayed_work_pending() is then
> false, so the cancel is skipped. The running instance finishes after
> the disable, sees the sink report scrambling off, writes the SCDC
> scrambling and clock ratio bits back on, and queues itself again. The
> sink is left configured for a scrambled 1/40 link that no longer exists
> and the work keeps running until the next enable.
> 
> cancel_delayed_work_sync() handles both states: it waits for a running
> instance and blocks it from queueing itself again.
> 
> Fixes: 257d36d493e9 ("drm/vc4: hdmi: Add a workqueue to set scrambling")
> Assisted-by: LLM
> Signed-off-by: Lucas Tanure <lucas.tanure@neat.no>

Reviewed-by: Maíra Canal <mcanal@igalia.com>

Best regards,
- Maíra
> ---
>   drivers/gpu/drm/vc4/vc4_hdmi.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 2cc46036f11d..4a386e053d3f 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -843,8 +843,7 @@ static void vc4_hdmi_disable_scrambling(struct drm_encoder *encoder)
>   
>   	vc4_hdmi->scdc_enabled = false;
>   
> -	if (delayed_work_pending(&vc4_hdmi->scrambling_work))
> -		cancel_delayed_work_sync(&vc4_hdmi->scrambling_work);
> +	cancel_delayed_work_sync(&vc4_hdmi->scrambling_work);
>   
>   	if (!drm_dev_enter(drm, &idx))
>   		return;