[PATCH] media: platform: mtk-mdp3: add WQ_PERCPU to alloc_workqueue users

[AngeloGioacchino Del Regno]

Il 07/11/25 15:13, Marco Crivellari ha scritto:
> 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.
> 
> alloc_workqueue() treats all queues as per-CPU by default, while unbound
> workqueues must opt-in via WQ_UNBOUND.
> 
> This default is suboptimal: most workloads benefit from unbound queues,
> allowing the scheduler to place worker threads where they’re needed and
> reducing noise when CPUs are isolated.
> 
> This continues the effort to refactor workqueue APIs, which began with
> the introduction of new workqueues and a new alloc_workqueue flag in:
> 
> commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
> 
> This change adds a new WQ_PERCPU flag to explicitly request
> alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.
> 
> With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
> any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
> must now use WQ_PERCPU.
> 
> Once migration is complete, WQ_UNBOUND can be removed and unbound will
> become the implicit default.
> 
> Suggested-by: Tejun Heo <tj at kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari at suse.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>

> ---
>   drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> index 6559d72d5d42..9083367ae2e4 100644
> --- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> +++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> @@ -255,14 +255,16 @@ static int mdp_probe(struct platform_device *pdev)
>   		goto err_free_mutex;
>   	}
>   
> -	mdp->job_wq = alloc_workqueue(MDP_MODULE_NAME, WQ_FREEZABLE, 0);
> +	mdp->job_wq = alloc_workqueue(MDP_MODULE_NAME,
> +				      WQ_FREEZABLE | WQ_PERCPU, 0);
>   	if (!mdp->job_wq) {
>   		dev_err(dev, "Unable to create job workqueue\n");
>   		ret = -ENOMEM;
>   		goto err_deinit_comp;
>   	}
>   
> -	mdp->clock_wq = alloc_workqueue(MDP_MODULE_NAME "-clock", WQ_FREEZABLE,
> +	mdp->clock_wq = alloc_workqueue(MDP_MODULE_NAME "-clock",
> +					WQ_FREEZABLE | WQ_PERCPU,
>   					0);
>   	if (!mdp->clock_wq) {
>   		dev_err(dev, "Unable to create clock workqueue\n");