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From:   Karol Herbst <kherbst@redhat.com>
Date:   Tue, 17 Jul 2018 14:10:17 +0200
Message-ID: <CACO55tvMRd8jpmq8-J4eyqzqHeoVgnbRLYEqvYBhrVJ9O9+gXA@mail.gmail.com>
Subject: Re: [Nouveau] [PATCH 4/5] drm/nouveau: Grab RPM ref when i2c bus is
 in use
To:     Ben Skeggs <skeggsb@gmail.com>
Cc:     Lyude Paul <lyude@redhat.com>, Dave Airlie <airlied@linux.ie>,
        nouveau <nouveau@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Ben Skeggs <bskeggs@redhat.com>
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On Tue, Jul 17, 2018 at 1:54 PM, Ben Skeggs <skeggsb@gmail.com> wrote:
> On Tue, 17 Jul 2018 at 20:18, Karol Herbst <kherbst@redhat.com> wrote:
>>
>> mhh, we shouldn't call to Linux APIs from within of nvkm. Rather gaurd
>> the Linux glue code to the i2c stuff instead, but this is all done
>> from inside of nvkm. I think we should move it out into
>> drm/nouveau/nouveau_i2c.c and do the handling there.
> Huh?  No, this is completely fine.
>

okay, then the the two patches adding that guard code is reviewed-by me

>>
>> On Tue, Jul 17, 2018 at 1:59 AM, Lyude Paul <lyude@redhat.com> wrote:
>> > The i2c bus can be both accessed by DRM itself, along with any of it's
>> > devnodes (/sys/class/i2c). So, we need to make sure that all codepaths
>> > using the i2c bus keep the GPU resumed.
>> >
>> > Signed-off-by: Lyude Paul <lyude@redhat.com>
>> > Cc: Karol Herbst <karolherbst@gmail.com>
>> > Cc: stable@vger.kernel.org
>> > ---
>> >  drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bus.c | 12 +++++++++++-
>> >  1 file changed, 11 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bus.c b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bus.c
>> > index 807a2b67bd64..1de48c990b80 100644
>> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bus.c
>> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bus.c
>> > @@ -119,18 +119,28 @@ nvkm_i2c_bus_release(struct nvkm_i2c_bus *bus)
>> >         BUS_TRACE(bus, "release");
>> >         nvkm_i2c_pad_release(pad);
>> >         mutex_unlock(&bus->mutex);
>> > +       pm_runtime_put_autosuspend(pad->i2c->subdev.device->dev);
>> >  }
>> >
>> >  int
>> >  nvkm_i2c_bus_acquire(struct nvkm_i2c_bus *bus)
>> >  {
>> >         struct nvkm_i2c_pad *pad = bus->pad;
>> > +       struct device *dev = pad->i2c->subdev.device->dev;
>> >         int ret;
>> > +
>> >         BUS_TRACE(bus, "acquire");
>> > +
>> > +       ret = pm_runtime_get_sync(dev);
>> > +       if (ret < 0 && ret != -EACCES)
>> > +               return ret;
>> > +
>> >         mutex_lock(&bus->mutex);
>> >         ret = nvkm_i2c_pad_acquire(pad, NVKM_I2C_PAD_I2C);
>> > -       if (ret)
>> > +       if (ret) {
>> >                 mutex_unlock(&bus->mutex);
>> > +               pm_runtime_put_autosuspend(dev);
>> > +       }
>> >         return ret;
>> >  }
>> >
>> > --
>> > 2.17.1
>> >
>> > _______________________________________________
>> > Nouveau mailing list
>> > Nouveau@lists.freedesktop.org
>> > https://lists.freedesktop.org/mailman/listinfo/nouveau
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