Hi, Michael:
Michael Walle <[email protected]> 於 2023年9月5日 週二 下午4:49寫道：
>
> drm_crtc_from_index(0) might return NULL if there are no CRTCs
> registered at all which will lead to a kernel oops in
> mtk_drm_crtc_dma_dev_get(). Add the missing return value check.
Applied to mediatek-drm-fixes [1], thanks.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-fixes
Regards,
Chun-Kuang.
>
> Fixes: 0d9eee9118b7 ("drm/mediatek: Add drm ovl_adaptor sub driver for MT8195")
> Signed-off-by: Michael Walle <[email protected]>
> Reviewed-by: Nícolas F. R. A. Prado <[email protected]>
> Tested-by: Nícolas F. R. A. Prado <[email protected]>
> Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
> ---
> v4:
> - collected tags
> v3:
> - none
> v2:
> - collected tags
> - fixed typos
> ---
> drivers/gpu/drm/mediatek/mtk_drm_drv.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> index 93552d76b6e7..2c582498817e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> @@ -420,6 +420,7 @@ static int mtk_drm_kms_init(struct drm_device *drm)
> struct mtk_drm_private *private = drm->dev_private;
> struct mtk_drm_private *priv_n;
> struct device *dma_dev = NULL;
> + struct drm_crtc *crtc;
> int ret, i, j;
>
> if (drm_firmware_drivers_only())
> @@ -494,7 +495,9 @@ static int mtk_drm_kms_init(struct drm_device *drm)
> }
>
> /* Use OVL device for all DMA memory allocations */
> - dma_dev = mtk_drm_crtc_dma_dev_get(drm_crtc_from_index(drm, 0));
> + crtc = drm_crtc_from_index(drm, 0);
> + if (crtc)
> + dma_dev = mtk_drm_crtc_dma_dev_get(crtc);
> if (!dma_dev) {
> ret = -ENODEV;
> dev_err(drm->dev, "Need at least one OVL device\n");
> --
> 2.39.2
>