Re: [PATCH 09/10] drm/tidss: Drop WARN_ON() from tidss_runtime_put()

[Swamil Jain]

On 9/3/26 17:39, Tomi Valkeinen wrote:
> At the moment tidss driver has a WARN_ON(r < 0) for the
> pm_runtime_put_autosuspend() return value, to catch unexpected
> situations, and at the moment we never hit that warn. However, with the
> upcoming change in tidss_oldi.c to change the OLDI to an auxiliary
> device, we will get a child-parent relationship between tidss and OLDI.
>
> The OLDI aux devices are children of the DSS device, so when an OLDI is
> active, the DSS's child_count is non-zero, and
> pm_runtime_put_autosuspend() on the DSS device returns -EBUSY. Which
> then triggers the WARN_ON().
>
> To avoid that, drop the WARN_ON. The -EBUSY is not an error, and it's a
> normal situation with parent-child devices. Also, with a quick grep, it
> looks like almost no driver in the kernel checks
> pm_runtime_put_autosuspend()'s return value.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> ---

Reviewed-by: Swamil Jain <s-jain1@xxxxxx>

>   drivers/gpu/drm/tidss/tidss_drv.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/tidss/tidss_drv.c b/drivers/gpu/drm/tidss/tidss_drv.c
> index 5cb3e746aeb3..44b0b009c29a 100644
> --- a/drivers/gpu/drm/tidss/tidss_drv.c
> +++ b/drivers/gpu/drm/tidss/tidss_drv.c
> @@ -40,10 +40,7 @@ int tidss_runtime_get(struct tidss_device *tidss)
>   
>   void tidss_runtime_put(struct tidss_device *tidss)
>   {
> -	int r;
> -
> -	r = pm_runtime_put_autosuspend(tidss->dev);
> -	WARN_ON(r < 0);
> +	pm_runtime_put_autosuspend(tidss->dev);
>   }
>   
>   static int __maybe_unused tidss_pm_runtime_suspend(struct device *dev)