Hi,
sorry for the late review. I've been away for a few days.
Am 12.04.25 um 09:00 schrieb Thierry Reding:
From: Thierry Reding <tred...@nvidia.com>
Recent generations of Tegra have moved the display components outside of
host1x, leading to a device that has no CRTCs attached and hence doesn't
support any of the modesetting functionality. When this is detected, the
driver clears the DRIVER_MODESET and DRIVER_ATOMIC flags for the device.
Unfortunately, this causes the following errors during boot:
[ 15.418958] ERR KERN drm drm: [drm] *ERROR* Failed to register
client: -95
[ 15.425311] WARNING KERN drm drm: [drm] Failed to set up DRM client;
error -95
These originate from the fbdev client checking for the presence of the
DRIVER_MODESET flag and returning -EOPNOTSUPP. However, if a driver does
not support DRIVER_MODESET this is entirely expected and the error isn't
helpful.
One solution would have been to conditionally call drm_client_setup()
only if modesetting is supported. This seems a bit redundant, however,
and could further complicate things if ever any DRM clients are added
that do not rely on modesetting.
These default in-kernel clients are all somewhat legacy by definition
and the only viable use cases involve display output. There won't be any
clients that don't output to the display. Best would be to put that
check around drm_client_setup() in the tegra driver. [1]
if (drm->driver_features & MODESET)
drm_client_setup()
[1]
https://elixir.bootlin.com/linux/v6.14.5/source/drivers/gpu/drm/tegra/drm.c#L1274
If you want to get fancy, you could also add that test at the very top
of drm_client_setup() itself; with a drm_dbg() statement noting the
absense of modesetting.
Best regards
Thomas
Instead, simply add an extra check to ignore this expected error and
skip the fbdev client registration.
Reported-by: Jonathan Hunter <jonath...@nvidia.com>
Signed-off-by: Thierry Reding <tred...@nvidia.com>
---
drivers/gpu/drm/clients/drm_fbdev_client.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/clients/drm_fbdev_client.c
b/drivers/gpu/drm/clients/drm_fbdev_client.c
index f894ba52bdb5..8c8552ed912e 100644
--- a/drivers/gpu/drm/clients/drm_fbdev_client.c
+++ b/drivers/gpu/drm/clients/drm_fbdev_client.c
@@ -152,7 +152,11 @@ int drm_fbdev_client_setup(struct drm_device *dev, const
struct drm_format_info
ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
if (ret) {
- drm_err(dev, "Failed to register client: %d\n", ret);
+ if (ret != -EOPNOTSUPP)
+ drm_err(dev, "Failed to register client: %d\n", ret);
+ else
+ ret = 0;
+
goto err_drm_client_init;
}
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
