From: Thierry Reding <treding@xxxxxxxxxx>
Tegra DRM doesn't support display on Tegra234 and later, so make sure
not to remove any existing framebuffers in that case.
v2: - add comments explaining how this situation can come about
- clear DRIVER_MODESET and DRIVER_ATOMIC feature bits
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
drivers/gpu/drm/tegra/drm.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index b1e1a78e30c6..2e1cfe6f6d74 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -1220,9 +1220,26 @@ static int host1x_drm_probe(struct host1x_device *dev)
drm_mode_config_reset(drm);
- err = drm_aperture_remove_framebuffers(&tegra_drm_driver);
- if (err < 0)
- goto hub;
+ /*
+ * Only take over from a potential firmware framebuffer if any CRTCs
+ * have been registered. This must not be a fatal error because there
+ * are other accelerators that are exposed via this driver.
+ *
+ * Another case where this happens is on Tegra234 where the display
+ * hardware is no longer part of the host1x complex, so this driver
+ * will not expose any modesetting features.
+ */
+ if (drm->mode_config.num_crtc > 0) {
+ err = drm_aperture_remove_framebuffers(&tegra_drm_driver);
+ if (err < 0)
+ goto hub;
+ } else {
+ /*
+ * Indicate to userspace that this doesn't expose any display
+ * capabilities.
+ */
+ drm->driver_features &= ~(DRIVER_MODESET | DRIVER_ATOMIC);
+ }
err = drm_dev_register(drm, 0);
if (err < 0)
--
2.43.2
