Re: [PATCH v12,2/3] drm: mediatek: Set dpi format in mmsys

[xinlei.lee <xinlei.lee@mediatek.com>]

On Fri, 2022-10-21 at 11:39 -0400, Nícolas F. R. A. Prado wrote:
> On Fri, Oct 21, 2022 at 08:18:25PM +0800, xinlei.lee wrote:
> > On Thu, 2022-10-20 at 12:40 -0400, Nícolas F. R. A. Prado wrote:
> > > On Wed, Oct 19, 2022 at 10:52:15AM +0800, xinlei.lee@mediatek.com
> > > wrote:
> 
> [..]
> > > > @@ -448,8 +453,12 @@ static void mtk_dpi_dual_edge(struct
> > > > mtk_dpi
> > > > *dpi)
> > > >  		mtk_dpi_mask(dpi, DPI_OUTPUT_SETTING,
> > > >  			     dpi->output_fmt ==
> > > > MEDIA_BUS_FMT_RGB888_2X12_LE ?
> > > >  			     EDGE_SEL : 0, EDGE_SEL);
> > > > +		if (dpi->conf->edge_cfg_in_mmsys)
> > > > +			mtk_mmsys_ddp_dpi_fmt_config(dpi-
> > > > >mmsys_dev,
> > > > MTK_DPI_RGB888_DDR_CON);
> > > >  	} else {
> > > >  		mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN |
> > > > DDR_4PHASE,
> > > > 0);
> > > > +		if (dpi->conf->edge_cfg_in_mmsys)
> > > > +			mtk_mmsys_ddp_dpi_fmt_config(dpi-
> > > > >mmsys_dev,
> > > > MTK_DPI_RGB888_SDR_CON);
> > > 
> > > I know this isn't one of the formats supported by MT8186, but
> > > since
> > > we're using
> > > platform-agnostic formats now... This else branch in theory could
> > > also run for a
> > > format like MEDIA_BUS_FMT_YUYV8_1X16. Would it make sense to set
> > > MTK_DPI_RGB888_SDR_CON in that case?
> > > 
> > > Thanks,
> > > Nícolas
> > > 
> > > >  	}
> > > 
> > > [..]
> > 
> > Hi Nícolas:
> > 
> > Thanks for your review!
> >  
> > You are right, I understand you think this MTK_DPI_RGB888_SDR_CON 
> > format seems useless as it will not be set, I confirmed with the 
> > designer how the setting in mmsys affects the output format of the 
> > MT8186, this mmsys setting will not be used by other ICs.
> > 
> > As mentioned earlier, the mmsys setting will make the MT8186dpi
> > have 
> > four output formats, even though the MT8186 dpi may not use them
> > all.
> > 
> > So what needs to change here?
> 
> We could check that the format in the else path is a single edge
> RGB888 format
> like MEDIA_BUS_FMT_RGB888_1X24 before setting the mmsys config, but
> there are
> also other formats possible, and I actually don't think it's worth it
> to
> complicate the logic further to protect from an edge-case that can't
> be hit
> yet...
> 
> So just leave it as it is. We can worry about it when/if a non-RGB888 
> single
> edge format needs to be setup on mmsys.
> 
> So,
> 
> Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> 
> Thanks,
> Nícolas


Hi Nícolas:

Thanks for your review!

Best Regards!
xinlei