Hi Mauro,
On Sat, Apr 24, 2021 at 8:46 AM Mauro Carvalho Chehab
<mchehab+huawei@xxxxxxxxxx> wrote:
> Commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> added pm_runtime_resume_and_get() in order to automatically handle
> dev->power.usage_count decrement on errors.
>
> Use the new API, in order to cleanup the error check logic.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Thanks for your patch!
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -408,7 +408,7 @@ static void rcsi2_enter_standby(struct rcar_csi2 *priv)
>
> static void rcsi2_exit_standby(struct rcar_csi2 *priv)
> {
> - pm_runtime_get_sync(priv->dev);
> + pm_runtime_resume_and_get(priv->dev);
I believe this part is incorrect: on failure[*], the refcount will now
be decremented, and in a subsequent call to rcsi2_enter_standby(), the
refcount will be decremented again due to the call to pm_runtime_put().
[*] On e.g. R-Car SoCs, this can never fail. This is the reason why
many R-Car (and SuperH) drivers never check the result of
pm_runtime_get_sync(). So the refcount "imbalances" were actually
introduced by the various "clean up" patches to add return value
checking, which now need another round of fixing...
> reset_control_deassert(priv->rstc);
> }
> --- a/drivers/media/platform/rcar-vin/rcar-dma.c
> +++ b/drivers/media/platform/rcar-vin/rcar-dma.c
> @@ -1458,11 +1458,9 @@ int rvin_set_channel_routing(struct rvin_dev *vin, u8 chsel)
> u32 vnmc;
> int ret;
>
> - ret = pm_runtime_get_sync(vin->dev);
> - if (ret < 0) {
> - pm_runtime_put_noidle(vin->dev);
> + ret = pm_runtime_resume_and_get(vin->dev);
> + if (ret < 0)
> return ret;
> - }
This change (and the change below) is correct, as the logic before/after
is equivalent.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
