2025년 6월 27일 (금) 오전 4:21, Kaustabh Chakraborty kauschluss@disroot.org님이 작성:
If there's support for another console device (such as a TTY serial), the kernel occasionally panics during boot. The panic message and a relevant snippet of the call stack is as follows:
Unable to handle kernel NULL pointer dereference at virtual address 000000000000000 Call trace: drm_crtc_handle_vblank+0x10/0x30 (P) decon_irq_handler+0x88/0xb4 [...]
It seems that if the display is already enabled by the bootloader during the boot process, a vblank interrupt may be triggered before the initialization of drm_dev is complete. This could be the root cause of the issue.
Applied.
Thanks, Inki Dae
Otherwise, the panics don't happen. This indicates that it's some sort of race condition.
Add a check to validate if the drm device can handle vblanks before calling drm_crtc_handle_vblank() to avoid this.
Cc: stable@vger.kernel.org Fixes: 96976c3d9aff ("drm/exynos: Add DECON driver") Signed-off-by: Kaustabh Chakraborty kauschluss@disroot.org
drivers/gpu/drm/exynos/exynos7_drm_decon.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/exynos/exynos7_drm_decon.c b/drivers/gpu/drm/exynos/exynos7_drm_decon.c index 43bcbe2e2917df43d7c2d27a9771e892628dd682..c0c0f23169c993ac315fc8d7bcbd09ea6ec9966a 100644 --- a/drivers/gpu/drm/exynos/exynos7_drm_decon.c +++ b/drivers/gpu/drm/exynos/exynos7_drm_decon.c @@ -636,6 +636,10 @@ static irqreturn_t decon_irq_handler(int irq, void *dev_id) if (!ctx->drm_dev) goto out;
/* check if crtc and vblank have been initialized properly */if (!drm_dev_has_vblank(ctx->drm_dev))goto out;if (!ctx->i80_if) { drm_crtc_handle_vblank(&ctx->crtc->base);-- 2.49.0