linux-kernel - Re: [PATCH] soc: mediatek: mtk-mmsys: Add support for MT6795 Helio X10

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Message-ID: <4b5d6607b90f3e36fce7e61e1768da55693546aa.camel@mediatek.com>
Date:   Mon, 16 May 2022 17:50:39 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, <matthias.bgg@...il.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <konrad.dybcio@...ainline.org>,
        <marijn.suijten@...ainline.org>, <martin.botka@...ainline.org>,
        <~postmarketos/upstreaming@...ts.sr.ht>,
        <phone-devel@...r.kernel.org>, <paul.bouchara@...ainline.org>,
        <kernel@...labora.com>
Subject: Re: [PATCH] soc: mediatek: mtk-mmsys: Add support for MT6795 Helio
 X10

On Mon, 2022-05-16 at 10:44 +0200, AngeloGioacchino Del Regno wrote:
> Il 16/05/22 07:43, CK Hu ha scritto:
> > Hi, Angelo:
> > 
> > On Fri, 2022-05-13 at 19:03 +0200, AngeloGioacchino Del Regno
> > wrote:
> > > Add MM support for the MT6795 SoC, using the mmsys default
> > > routing
> > > table.
> > > 
> > > Signed-off-by: AngeloGioacchino Del Regno <
> > > angelogioacchino.delregno@...labora.com>
> > > ---
> > > 
> > > In order for this patch to have any meaning and functionality, it
> > > is
> > > required to also have in-tree the [1] MT6795 clocks series, even
> > > though that's not required to actually compile this code.
> > > 
> > > [1]
> > > 
https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/list/?series=641493__;!!CTRNKA9wMg0ARbw!ywDb_Gj4oV0iYHK_PbtJSNejzsJGlFVjX-1O0G1mR0vZX_5VeMtlZJ_AS6K_Mg$
> > >   
> > > 
> > >   drivers/soc/mediatek/mtk-mmsys.c | 11 +++++++++++
> > >   1 file changed, 11 insertions(+)
> > > 
> > > diff --git a/drivers/soc/mediatek/mtk-mmsys.c
> > > b/drivers/soc/mediatek/mtk-mmsys.c
> > > index 06d8e83a2cb5..38b36b881a3b 100644
> > > --- a/drivers/soc/mediatek/mtk-mmsys.c
> > > +++ b/drivers/soc/mediatek/mtk-mmsys.c
> > > @@ -57,6 +57,13 @@ static const struct mtk_mmsys_match_data
> > > mt6779_mmsys_match_data = {
> > >   	},
> > >   };
> > >   
> > > +static const struct mtk_mmsys_driver_data
> > > mt6795_mmsys_driver_data =
> > > {
> > > +	.clk_driver = "clk-mt6795-mm",
> > > +	.routes = mmsys_default_routing_table,
> > 
> > mt6795 should have its own routing table instead of default one.
> > The
> > default one is used for mt8173, mt2701, mt2712 which no one knows
> > how
> > to separate them. If you don't know the routing table of mt6795,
> > just
> > left this as NULL.
> > 
> 
> Hello CK,
> 
> I agree with you, in fact the first test that I've done was with
> leaving
> routes to NULL, but that did not work (I couldn't get the display to
> work),
> while assigning the default routing table resulted in having a
> working
> internal (DSI) display et al, which is why I have done that.
> 
> I am sure that this may be a quirk that is required due to my
> platform's
> bootloader, but still, it won't work otherwise.
> 
> If anyone from MediaTek wants to help with providing a better
> solution for
> that, you're welcome to - but otherwise, my proposal is to configure
> MT6795
> with that default routing table and eventually come back to this
> later if
> any issue with this gets discovered... I couldn't find any, though.

So you have a drm driver which support mt6795 and it would call
mtk_mmsys_ddp_connect() to setup routing routing register. You could
generate mt6795 routing table from default one by partial element that
you use in mt6795. I think this table would be smaller than the default
one.

Regards,
CK

> 
> Cheers,
> Angelo
>