Patch "drm/mediatek: Detect CMDQ execution timeout" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/mediatek: Detect CMDQ execution timeout

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-mediatek-detect-cmdq-execution-timeout.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e00118f8bbf5550fc398d49351084f1d9cd2726b
Author: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
Date:   Wed Oct 27 10:18:54 2021 +0800

    drm/mediatek: Detect CMDQ execution timeout
    
    [ Upstream commit eaf80126aba6fd1754837eec91e4c8bbd58ae52e ]
    
    CMDQ is used to update display register in vblank period, so
    it should be execute in next 2 vblank. One vblank interrupt
    before send message (occasionally) and one vblank interrupt
    after cmdq done. If it fail to execute in next 3 vblank,
    tiemout happen.
    
    Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
    Signed-off-by: jason-jh.lin <jason-jh.lin@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index e23e3224ac67..dad1f85ee315 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -54,6 +54,7 @@ struct mtk_drm_crtc {
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
 	struct cmdq_client		cmdq_client;
 	u32				cmdq_event;
+	u32				cmdq_vblank_cnt;
 #endif
 
 	struct device			*mmsys_dev;
@@ -227,7 +228,10 @@ struct mtk_ddp_comp *mtk_drm_ddp_comp_for_plane(struct drm_crtc *crtc,
 static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
 {
 	struct cmdq_cb_data *data = mssg;
+	struct cmdq_client *cmdq_cl = container_of(cl, struct cmdq_client, client);
+	struct mtk_drm_crtc *mtk_crtc = container_of(cmdq_cl, struct mtk_drm_crtc, cmdq_client);
 
+	mtk_crtc->cmdq_vblank_cnt = 0;
 	cmdq_pkt_destroy(data->pkt);
 }
 #endif
@@ -483,6 +487,15 @@ static void mtk_drm_crtc_update_config(struct mtk_drm_crtc *mtk_crtc,
 					   cmdq_handle->pa_base,
 					   cmdq_handle->cmd_buf_size,
 					   DMA_TO_DEVICE);
+		/*
+		 * CMDQ command should execute in next 3 vblank.
+		 * One vblank interrupt before send message (occasionally)
+		 * and one vblank interrupt after cmdq done,
+		 * so it's timeout after 3 vblank interrupt.
+		 * If it fail to execute in next 3 vblank, timeout happen.
+		 */
+		mtk_crtc->cmdq_vblank_cnt = 3;
+
 		mbox_send_message(mtk_crtc->cmdq_client.chan, cmdq_handle);
 		mbox_client_txdone(mtk_crtc->cmdq_client.chan, 0);
 	}
@@ -499,11 +512,14 @@ static void mtk_crtc_ddp_irq(void *data)
 
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
 	if (!priv->data->shadow_register && !mtk_crtc->cmdq_client.chan)
+		mtk_crtc_ddp_config(crtc, NULL);
+	else if (mtk_crtc->cmdq_vblank_cnt > 0 && --mtk_crtc->cmdq_vblank_cnt == 0)
+		DRM_ERROR("mtk_crtc %d CMDQ execute command timeout!\n",
+			  drm_crtc_index(&mtk_crtc->base));
 #else
 	if (!priv->data->shadow_register)
-#endif
 		mtk_crtc_ddp_config(crtc, NULL);
-
+#endif
 	mtk_drm_finish_page_flip(mtk_crtc);
 }