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

[Lyude Paul <lyude-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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

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