Non-atomic drivers like ast doesn't have connector->state set resulting
in a NULL pointer deref:
[ 29.609593] BUG: unable to handle kernel NULL pointer dereference at
0000000000000010
[ 29.609619] Call Trace:
[ 29.609630] ? drm_helper_probe_single_connector_modes+0x27f/0x680
[ 29.609640] drm_setup_crtcs+0x431/0xd80 [drm_kms_helper]
[ 29.753065] __drm_fb_helper_initial_config_and_unlock+0x6f/0x6a0
[ 29.753160] ? drm_modeset_unlock_all+0x31/0x50 [drm]
[ 29.765758] ast_fbdev_init+0xa8/0xc0 [ast]
[ 29.765762] ast_driver_load.cold.7+0x2b3/0xe11 [ast]
[ 29.765775] drm_dev_register+0x111/0x150 [drm]
Fix by bailing out if the driver does not support atomic modesetting.
Fixes: 09ded8af57bc ("drm/i915/fbdev: Move intel_fb_initial_config() to fbdev
helper")
Reported-by: Thomas Zimmermann <tzimmerm...@suse.de>
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
Cc: Jani Nikula <jani.nik...@linux.intel.com>
Signed-off-by: Noralf Trønnes <nor...@tronnes.org>
---
drivers/gpu/drm/drm_fb_helper.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 2339f0f8f5a8..899c2eca26d1 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -2588,6 +2588,9 @@ static bool drm_fb_helper_firmware_config(struct
drm_fb_helper *fb_helper,
int num_connectors_detected = 0;
struct drm_modeset_acquire_ctx ctx;
+ if (!drm_drv_uses_atomic_modeset(dev))
+ return false;
+
save_enabled = kcalloc(count, sizeof(bool), GFP_KERNEL);
if (!save_enabled)
return false;
--
2.20.1
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