linux-kernel - Re: [PATCH v2 04/11] drm/mediatek: Add OVL compatible name for MT8195

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Date:   Wed, 11 Oct 2023 09:38:02 +0000
From:   Shawn Sung (宋孝謙) 
        <Shawn.Sung@...iatek.com>
To:     CK Hu (胡俊光) <ck.hu@...iatek.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "wenst@...omium.org" <wenst@...omium.org>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "airlied@...il.com" <airlied@...il.com>
Subject: Re: [PATCH v2 04/11] drm/mediatek: Add OVL compatible name for MT8195

Hi, Angelo and CK,

On Mon, 2023-09-18 at 11:21 +0200, AngeloGioacchino Del Regno wrote:
> Il 18/09/23 11:09, CK Hu (胡俊光) ha scritto:
> > On Mon, 2023-09-18 at 16:42 +0800, Hsiao Chien Sung wrote:
> > > Add OVL compatible name for MT8195.
> > 
> > Reviewed-by: CK Hu <ck.hu@...iatek.com>
> > 
> > but it's weird to put this patch into IGT series. Without this
> > patch,
> > mt8195 drm driver does not work not only IGT.
> > 
> 
> The driver does work because the devicetree node declares two
> compatibles,
> "mediatek,mt8195-disp-ovl", "mediatek,mt8183-disp-ovl" where the
> second
> compatible is matched in mtk_drm_drv, and the first is matched in
> mtk_disp_ovl
> as both are platform_driver.
> 
> This commit is not necessary, even... :-)
> 
> Regards,
> Angelo
> 
> > Regards,
> > CK
> > 
> > > 
> > > Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
> > > ---
> > >   drivers/gpu/drm/mediatek/mtk_drm_drv.c | 2 ++
> > >   1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > > b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > > index 93552d76b6e7..7759a06e5c0e 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > > @@ -715,6 +715,8 @@ static const struct of_device_id
> > > mtk_ddp_comp_dt_ids[] = {
> > >   	  .data = (void *)MTK_DISP_OVL },
> > >   	{ .compatible = "mediatek,mt8192-disp-ovl",
> > >   	  .data = (void *)MTK_DISP_OVL },
> > > +	{ .compatible = "mediatek,mt8195-disp-ovl",
> > > +	  .data = (void *)MTK_DISP_OVL },
> > >   	{ .compatible = "mediatek,mt8183-disp-ovl-2l",
> > >   	  .data = (void *)MTK_DISP_OVL_2L },
> > >   	{ .compatible = "mediatek,mt8192-disp-ovl-2l",
> 
> 

Please refer to c6aa5f1fb505. This is the main reason why we have to
use MT8195 instead of MT8183/MT8192. Most of the formats required by
IGT is not supported.

Without this commit, DRM won't work after changing the compatible name 
of ovl0 to "mediatek,mt8195-disp-ovl" in the dts.

Thanks,
Shawn