Re: [PATCH v17 13/21] drm/mediatek: add display merge async reset control

[Nancy.Lin <nancy.lin@mediatek.com>]

Hi Philipp,

Thanks for the review.

On Mon, 2022-04-25 at 11:58 +0200, Philipp Zabel wrote:
> On Sa, 2022-04-16 at 10:07 +0800, Nancy.Lin wrote:
> > Add merge async reset control in mtk_merge_stop. Async hw doesn't
> > do self
> > reset on each sof signal(start of frame), so need to reset the
> > async to
> > clear the hw status for the next merge start.
> > 
> > Signed-off-by: Nancy.Lin <nancy.lin@mediatek.com>
> > Reviewed-by: CK Hu <ck.hu@mediatek.com>
> > Reviewed-by: AngeloGioacchino Del Regno <
> > angelogioacchino.delregno@collabora.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_disp_merge.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> > b/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> > index 9dca145cfb71..177473fa8160 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_merge.c
> > @@ -8,6 +8,7 @@
> >  #include <linux/of_device.h>
> >  #include <linux/of_irq.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/reset.h>
> >  #include <linux/soc/mediatek/mtk-cmdq.h>
> >  
> > 
> > 
> > 
> >  #include "mtk_drm_ddp_comp.h"
> > @@ -79,6 +80,9 @@ void mtk_merge_stop(struct device *dev)
> >  	struct mtk_disp_merge *priv = dev_get_drvdata(dev);
> >  
> > 
> > 
> > 
> >  	mtk_merge_stop_cmdq(dev, NULL);
> > +
> > +	if (priv->async_clk)
> > +		device_reset_optional(dev);
> 
> To avoid the overhead of looking up the reset control in the device
> tree every time, it would be better to request a reset control during
> probe using devm_reset_control_get_optional_exclusive(). Here you'd
> just call reset_control_reset().
> 
> regards
> Philipp

OK. I will refine it in the next revision.

Regards,
Nancy