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drm/exynos: exynos7_drm_decon: add vblank check in IRQ handling

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commit b846350aa272de99bf6fecfa6b08e64ebfb13173 upstream.

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
    [...]

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: 96976c3d9a ("drm/exynos: Add DECON driver")
Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kaustabh Chakraborty
2025-06-27 00:50:30 +05:30
committed by Greg Kroah-Hartman
parent 416d681f49
commit a2130463fc
1 changed files with 4 additions and 0 deletions
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4
drivers/gpu/drm/exynos/exynos7_drm_decon.c
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@@ -595,6 +595,10 @@ 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);