Re: [PATCH v9 1/5] drm/mediatek: ovl: Fix XRGB format breakage for blend_modes unsupported SoCs

["Jason-JH Lin (林睿祥)" <Jason-JH.Lin@mediatek.com>]

On Tue, 2024-10-08 at 03:51 +0000, CK Hu (胡俊光) wrote:
> Hi, Jason:
> 
> On Mon, 2024-10-07 at 15:00 +0800, Jason-JH.Lin wrote:
> > If the constant alpha always enable, the SoCs that is not supported
> > the
> > ignore pixel alpha bit will still use constant alpha. That will
> > break
> > the original constant alpha setting of XRGB foramt for blend_modes
> > unsupported SoCs, such as MT8173.
> > 
> > Note that ignore pixel alpha bit is suppored if the SoC support the
> > blend_modes.
> > Make the constatnt alpha only enable when having a vliad blend_mode
> > or
> > setting the has_alpha to fix the downgrade issue.
> 
> It's alpha blending enable, not constant alpha enable.

OK, I'll correct the commit message.

> 
> > 
> > Fixes: bc46eb5d5d77 ("drm/mediatek: Support DRM plane alpha in
> > OVL")
> > Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> > b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> > index 89b439dcf3a6..8453a72f9e59 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> > @@ -473,8 +473,14 @@ void mtk_ovl_layer_config(struct device *dev,
> > unsigned int idx,
> >  
> >  	con = ovl_fmt_convert(ovl, fmt, blend_mode);
> >  	if (state->base.fb) {
> > -		con |= OVL_CON_AEN;
> >  		con |= state->base.alpha & OVL_CON_ALPHA;
> > +
> > +		/*
> > +		 * For blend_modes supported SoCs, always enable
> > constant alpha.
> > +		 * For blend_modes unsupported SoCs, enable constant
> > alpha when has_alpha is set.
> 
> It's alpha blending enable, not constant alpha enable.
> 
OK, I'll correct the comment.

Regards,
Jason-JH.Lin

> Regards,
> CK