Re: [PATCH] drm/vc4: hdmi: replace use of system_wq with system_percpu_wq

["Maíra Canal" <mcanal@igalia.com>]

Hi Marco,

On 05/11/25 07:11, Marco Crivellari wrote:
> Currently if a user enqueues a work item using schedule_delayed_work() the
> used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
> WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
> schedule_work() that is using system_wq and queue_work(), that makes use
> again of WORK_CPU_UNBOUND.
> 
> This lack of consistency cannot be addressed without refactoring the API.
> 
> This patch continues the effort to refactor worqueue APIs, which has begun
> with the change introducing new workqueues and a new alloc_workqueue flag:
> 
> commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
> 
> system_wq should be the per-cpu workqueue, yet in this name nothing makes
> that clear, so replace system_wq with system_percpu_wq.
> 
> The old wq (system_wq) will be kept for a few release cycles.
> 
> Suggested-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>

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

Will this patch go through DRM trees? If so, let me know and I can push
it to drm-misc-next.

Best regards,
- Maíra

> ---
>   drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 07c91b450f93..c39cf1530f23 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -745,7 +745,7 @@ static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
>   
>   	vc4_hdmi->scdc_enabled = true;
>   
> -	queue_delayed_work(system_wq, &vc4_hdmi->scrambling_work,
> +	queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
>   			   msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
>   }
>   
> @@ -794,7 +794,7 @@ static void vc4_hdmi_scrambling_wq(struct work_struct *work)
>   	drm_scdc_set_high_tmds_clock_ratio(connector, true);
>   	drm_scdc_set_scrambling(connector, true);
>   
> -	queue_delayed_work(system_wq, &vc4_hdmi->scrambling_work,
> +	queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
>   			   msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
>   }
>