linux-kernel - Re: [Nouveau] [PATCH v5 13/13] drm/nouveau: Call pm_runtime_get_noresume() from hpd handlers

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Message-ID: <CACO55tthZMOSpU00nAXTPjfN0hfLEejETV=jT9shRDgucEdg7Q@mail.gmail.com>
Date:   Sat, 11 Aug 2018 11:35:26 +0200
From:   Karol Herbst <kherbst@...hat.com>
To:     Lyude Paul <lyude@...hat.com>
Cc:     nouveau <nouveau@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org,
        Ben Skeggs <bskeggs@...hat.com>
Subject: Re: [Nouveau] [PATCH v5 13/13] drm/nouveau: Call pm_runtime_get_noresume()
 from hpd handlers

On Tue, Aug 7, 2018 at 10:39 PM, Lyude Paul <lyude@...hat.com> wrote:
> We can't and don't need to try resuming the device from our hotplug
> handlers, but hotplug events are generally something we'd like to keep
> the device awake for whenever possible. So, grab a PM ref safely in our
> hotplug handlers using pm_runtime_get_noresume() and mark the device as
> busy once we're finished.
>
> Signed-off-by: Lyude Paul <lyude@...hat.com>
> Cc: stable@...r.kernel.org
> Cc: Lukas Wunner <lukas@...ner.de>
> Cc: Karol Herbst <karolherbst@...il.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_connector.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
> index 8409c3f2c3a1..5a8e8c1ad647 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> @@ -1152,6 +1152,11 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
>         const char *name = connector->name;
>         struct nouveau_encoder *nv_encoder;
>
> +       /* Resuming the device here isn't possible; but the suspend PM ops
> +        * will wait for us to finish our work before disabling us so this
> +        * should be enough
> +        */
> +       pm_runtime_get_noresume(drm->dev->dev);

what happens when pm_runtime_get_noresume is called nd the device is
suspended already? Do we have to take care of this here as well (like
simply aborting) or is it fine as it is?

>         nv_connector->hpd_task = current;
>
>         if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
> @@ -1171,6 +1176,9 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
>         }
>
>         nv_connector->hpd_task = NULL;
> +
> +       pm_runtime_mark_last_busy(drm->dev->dev);
> +       pm_runtime_put_autosuspend(drm->dev->dev);
>         return NVIF_NOTIFY_KEEP;
>  }
>
> --
> 2.17.1
>
> _______________________________________________
> Nouveau mailing list
> Nouveau@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau

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