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

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Message-ID: <723b33c08e3cfed2dd2b8551b8c3db5c6ab3ddb2.camel@mediatek.com>
Date:   Thu, 12 Oct 2023 02:18:31 +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>,
        "airlied@...il.com" <airlied@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 04/11] drm/mediatek: Add OVL compatible name for MT8195

Hi Angelo,

On Wed, 2023-10-11 at 13:51 +0200, AngeloGioacchino Del Regno wrote:
> Il 11/10/23 11:38, Shawn Sung (宋孝謙) ha scritto:
> > 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
> 
> You don't have to change anything at all in the dts.
> 
> The current mt8195.dtsi declares:
> compatible = "mediatek,mt8195-disp-ovl", "mediatek,mt8183-disp-ovl";
> 
> ..this is enough to get the mediatek,mt8195-disp-ovl match in
> mtk_disp_ovl.
> 
> Regards,
> Angelo

We are running IGT on MT8188 and current patch is based on Kernel 6.1.

Regards,
Shawn