[PATCH 2/6] gpu: host1x: Avoid double device_add when clients already present

[Mikko Perttunen]

host1x_device_add looks through the idle clients list to populate
subdevs, and any matches entries are moved from the subdevs list
to the active list. If all subdevs are populated, device_add will
be called on the device. The secondary "subdevs list empty" check
will then incorrectly again call device_add.

However, this would require a convoluted scenario since clients don't
typically end up on the idle clients list.

Fix by checking whether the device was already added before adding
again.

Fixes: fab823d82ee5 ("gpu: host1x: Allow loading tegra-drm without enabled engines")
Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
---
 drivers/gpu/host1x/bus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
index f814eb4941c0..fe4af98e8fc6 100644
--- a/drivers/gpu/host1x/bus.c
+++ b/drivers/gpu/host1x/bus.c
@@ -508,7 +508,7 @@ static int host1x_device_add(struct host1x *host1x,
 	 * Add device even if there are no subdevs to ensure syncpoint functionality
 	 * is available regardless of whether any engine subdevices are present
 	 */
-	if (list_empty(&device->subdevs)) {
+	if (list_empty(&device->subdevs) && !device->registered) {
 		err = device_add(&device->dev);
 		if (err < 0)
 			dev_err(&device->dev, "failed to add device: %d\n", err);

-- 
2.53.0