Re: [Nouveau] [PATCH 4/5] drm/nouveau: Grab RPM ref when i2c bus is in use

[Karol Herbst]

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.

On Tue, Jul 17, 2018 at 1:59 AM, Lyude Paul <lyude@xxxxxxxxxx> 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@xxxxxxxxxx>
> Cc: Karol Herbst <karolherbst@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>  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
>
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