Re: [PATCH v10 1/2] dt-bindings: pinctrl: mt8195: add rsel define

From: zhiyong.tao <zhiyong.tao@mediatek.com>
To: Chen-Yu Tsai <wenst@chromium.org>
Cc: Rob Herring <robh+dt@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>, <mark.rutland@arm.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Sean Wang <sean.wang@kernel.org>,
	srv_heupstream <srv_heupstream@mediatek.com>,
	<hui.liu@mediatek.com>, Eddie Huang <eddie.huang@mediatek.com>,
	<light.hsieh@mediatek.com>, <biao.huang@mediatek.com>,
	<hongzhou.yang@mediatek.com>, <sean.wang@mediatek.com>,
	<seiya.wang@mediatek.com>, <devicetree@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>,
	 <linux-gpio@vger.kernel.org>
Subject: Re: [PATCH v10 1/2] dt-bindings: pinctrl: mt8195: add rsel define
Date: Thu, 29 Jul 2021 16:23:08 +0800	[thread overview]
Message-ID: <07388dac4e25e0f260725e8f80ba099d5aa80949.camel@mediatek.com> (raw)
In-Reply-To: <CAGXv+5F_-W4aNt0WVSDBGLo_t8orNUq59GMKk_4xVr+hMb9Ctg@mail.gmail.com>

On Mon, 2021-07-26 at 16:02 +0800, Chen-Yu Tsai wrote:
> On Thu, Jul 22, 2021 at 3:54 PM zhiyong tao <zhiyong.tao@mediatek.com
> > wrote:
> > 
> > On Tue, 2021-07-13 at 15:17 +0800, Chen-Yu Tsai wrote:
> > > Hi,
> > > 
> > > On Sat, Jul 10, 2021 at 4:17 PM Zhiyong Tao <
> > > zhiyong.tao@mediatek.com> wrote:
> > > > 
> > > > This patch adds rsel define for mt8195.
> > > > 
> > > > Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com>
> > > > ---
> > > >  include/dt-bindings/pinctrl/mt65xx.h | 9 +++++++++
> > > >  1 file changed, 9 insertions(+)
> > > > 
> > > > diff --git a/include/dt-bindings/pinctrl/mt65xx.h b/include/dt-
> > > > bindings/pinctrl/mt65xx.h
> > > > index 7e16e58fe1f7..f5934abcd1bd 100644
> > > > --- a/include/dt-bindings/pinctrl/mt65xx.h
> > > > +++ b/include/dt-bindings/pinctrl/mt65xx.h
> > > > @@ -16,6 +16,15 @@
> > > >  #define MTK_PUPD_SET_R1R0_10 102
> > > >  #define MTK_PUPD_SET_R1R0_11 103
> > > > 
> > > > +#define MTK_PULL_SET_RSEL_000  200
> > > > +#define MTK_PULL_SET_RSEL_001  201
> > > > +#define MTK_PULL_SET_RSEL_010  202
> > > > +#define MTK_PULL_SET_RSEL_011  203
> > > > +#define MTK_PULL_SET_RSEL_100  204
> > > > +#define MTK_PULL_SET_RSEL_101  205
> > > > +#define MTK_PULL_SET_RSEL_110  206
> > > > +#define MTK_PULL_SET_RSEL_111  207
> > > > +
> > > 
> > > Instead of all the obscure macros and the new custom "rsel"
> > > property,
> > > which BTW is not in the bindings, can't we just list the actual
> > > bias
> > > resistance of each setting? We could also migrate away from R1R0.
> > > 
> > 
> > ==>Hi Chenyu,
> > The rsel actual bias resistance of each setting:
> > 
> > MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD;
> > MTK_PULL_SET_RSEL_001:10k in PU, 5k in PD;
> > MTK_PULL_SET_RSEL_010:5k in PU, 75k in PD;
> > MTK_PULL_SET_RSEL_011:4k in PU, 5K in PD;
> > MTK_PULL_SET_RSEL_100:3k in PU, 75k in PD;
> > MTK_PULL_SET_RSEL_101:2k in PU, 5K in PD;
> > MTK_PULL_SET_RSEL_110:1.5k in PU, 75k in PD;
> > MTK_PULL_SET_RSEL_111:1k in PU, 5k in PD.
> > 
> > The rsel actual bias resistance is different between PU and PD.
> 
> Thanks. Somehow I missed this when looking through the datasheet.
> This
> encoding is interesting. Since it doesn't make sense to have both
> pull-up and pull-down, even though the hardware seems capable of
> doing
> so, I suppose the intent is to support 75k or 5k for pull-down, and
> (75k, 10k, 5k, 4k, 3k, 2k, 1.5k, 1k) for pull-up?
> 
> We could add these values to the binding so we could check for
> misuse.
> 
> The range of values seems to also cover those supported by the
> alternative R0/R1 settings. The values for kprow[01] and kpcol[01]
> seem to be different though.
> 
> We should get rid of the MTK_PUPD_SET_R1R0_* macros at the same time.
> They seem to be some magic values used with bias-pull-*, which is not
> how the properties should be used. At the same time, they overlap
> with
> mediatek,pull-* properties.
> 
> It would be great if we could standardize on the generic pinconf
> properties, and also use real values that fit the requirements of the
> properties, i.e. using real resistance values. I'm not sure if it
> would make sense to enumerate which pins support which configurations
> though.
> 
> 
> Thanks
> ChenYu
> 
> 
The rsel actual bias resistance of each setting is different in
different IC. we think that the define "MTK_PULL_SET_RSEL_000" is more
common for all different IC.

Thanks.

> > > Then we can specify the setting with the standard bias-pull-
> > > up/down
> > > properties [1].
> > > 
> > > Also, please ask internally if Mediatek could relicense all the
> > > header
> > > files that Mediatek has contributed under include/dt-
> > > bindings/pinctrl/ [2]
> > > to GPL-2.0 and BSD dual license. These files are part of the DT
> > > bindings
> > > and we really want them to be dual licensed as well, and not just
> > > the
> > > YAML files.
> > > 
> > 
> > ==> We will confirm it internally and reply it later.
> > 
> > Thanks.
> > > 
> > > Regards
> > > ChenYu
> > > 
> > > 
> > > [1] 
> > > https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml#L37
> > > [2] Note that a few files were contributed by other people
> > > 
> > > >  #define MTK_DRIVE_2mA  2
> > > >  #define MTK_DRIVE_4mA  4
> > > >  #define MTK_DRIVE_6mA  6
> > > > --
> > > > 2.18.0
> > > > _______________________________________________
> > > > Linux-mediatek mailing list
> > > > Linux-mediatek@lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek