Hi, Fei:
Fei Shao <fshao@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> wrote:
> >
> > From: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
> >
> > 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>
> > Reviewed-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
> > ---
> > 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)
>
>
>
>
> > + 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
> >
