Hi, Fei:
Fei Shao fshao@chromium.org 於 2021年10月28日 週四 上午11:19寫道：
Hi Chun-Kuang,
On Thu, Oct 28, 2021 at 7:47 AM Chun-Kuang Hu chunkuang.hu@kernel.org wrote:
Hi, Fei:
Fei Shao fshao@chromium.org 於 2021年10月27日 週三 下午5:32寫道：
Hi Jason,
On Wed, Oct 27, 2021 at 10:19 AM jason-jh.lin jason-jh.lin@mediatek.com wrote:
From: Chun-Kuang Hu chunkuang.hu@kernel.org
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@kernel.org Signed-off-by: jason-jh.lin jason-jh.lin@mediatek.com Reviewed-by: Chun-Kuang Hu chunkuang.hu@kernel.org
drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)
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)I think atomic_dec_and_test() does what you want to do here.
I think this operation is not necessary to be atomic operation, and this statement could be reduced to
else if (--mtk_crtc->cmdq_vblank_cnt == 0)
I was thinking about using existing helpers to wrap up the counter operations, but I agree that it's not necessary. Just dropping the redundant check would be good enough.
I find one thing so that I would like this version. If we do not check mtk_crtc->cmdq_vblank_cnt > 0, mtk_crtc->cmdq_vblank_cnt would decrease to minus. And one day it would round to positive. So I would pick this version instead of v6.
Regards, Chun-Kuang.
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); }
-- 2.18.0