Re: [PATCH v8 21/23] drm/mediatek: Fix underrun in VDO1 when switches off the layer

[CK Hu (胡俊光)]

Hi, Hsiao-chien:

On Mon, 2023-10-16 at 18:40 +0800, Hsiao Chien Sung wrote:
> Do not reset Merge while using CMDQ because reset API doesn't
> wait for frame done event as CMDQ does and could lead to
> underrun when the layer is switching off.

Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>

> 
> Fixes: aaf94f7c3ae6 ("drm/mediatek: Add display merge async reset
> control")
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_merge.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> b/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> index fd14a59bc951..c19fb1836034 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> @@ -104,7 +104,7 @@ void mtk_merge_stop_cmdq(struct device *dev,
> struct cmdq_pkt *cmdq_pkt)
>  	mtk_ddp_write(cmdq_pkt, 0, &priv->cmdq_reg, priv->regs,
>  		      DISP_REG_MERGE_CTRL);
>  
> -	if (priv->async_clk)
> +	if (!cmdq_pkt && priv->async_clk)
>  		reset_control_reset(priv->reset_ctl);
>  }
>