[Devel] [PATCH vz10] drm/virtio: decline the device with -ENODEV when modesetting is off

[Eva Kurchatova <eva.kurchatova@virtuozzo.com>]

Our kernels disable modesetting by default, see 7932a11226c8 ("drm:
Disable modeset by default"), so on a machine that was not booted with
"modeset" every KMS driver declines the device it was offered. Of 23
existing upstream drm drivers, 21 report -ENODEV in such case, which
really_probe() reports as "rejects match" at debug level. virtio_gpu
returns -EINVAL instead, which the same function reports as

  virtio_gpu virtio0: probe with driver virtio_gpu failed with error -22

at error level, for a device the driver was never going to drive. It is
the only device error in the log of an otherwise healthy machine, and
the devices/error_logs selftest reports it, correctly.

Return -ENODEV, as the other drivers do. Nothing else changes: the probe
still does not happen and no drm device appears.

https://virtuozzo.atlassian.net/browse/VSTOR-139680
Feature: fix vz kernel
Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 71c6ccad4b99..c9deef9f8af0 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -76,10 +76,10 @@ static int virtio_gpu_probe(struct virtio_device *vdev)
 	int ret;
 
 	if (drm_firmware_drivers_only() && virtio_gpu_modeset == -1)
-		return -EINVAL;
+		return -ENODEV;
 
 	if (virtio_gpu_modeset == 0)
-		return -EINVAL;
+		return -ENODEV;
 
 	/*
 	 * The virtio-gpu device is a virtual device that doesn't have DMA
-- 
2.55.0