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

From: zhiyong.tao <zhiyong.tao@mediatek.com>
To: Linus Walleij <linus.walleij@linaro.org>,
	Chen-Yu Tsai <wenst@chromium.org>
Cc: <zhiyong.tao@mediatek.com>, Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <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 <light.hsieh@mediatek.com>,
	Biao Huang <biao.huang@mediatek.com>,
	"Hongzhou Yang" <hongzhou.yang@mediatek.com>,
	Sean Wang <sean.wang@mediatek.com>,
	"Seiya Wang" <seiya.wang@mediatek.com>,
	Devicetree List <devicetree@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
	<linux-arm-kernel@lists.infradead.org>,
	"moderated list:ARM/Mediatek SoC support"
	<linux-mediatek@lists.infradead.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>
Subject: Re: [PATCH v10 1/2] dt-bindings: pinctrl: mt8195: add rsel define
Date: Tue, 17 Aug 2021 10:21:16 +0800	[thread overview]
Message-ID: <a7c8ab68ac3513865698cde27e665bdd554f459e.camel@mediatek.com> (raw)
In-Reply-To: <CACRpkdbZKh8cqqiDRUik6Ooo33e+feGwYsLjcLRvBQnT3x5M3A@mail.gmail.com>

On Tue, 2021-08-17 at 01:00 +0200, Linus Walleij wrote:
> On Mon, Aug 16, 2021 at 5:38 PM Chen-Yu Tsai <wenst@chromium.org>
> wrote:
> > On Mon, Aug 16, 2021 at 6:48 PM zhiyong.tao <
> > zhiyong.tao@mediatek.com> wrote:
> > > > I'll take that as "use SI units whenever possible and
> > > > reasonable".
> > > 
> > > ==> so It doesn't need to change the define, is it right?
> > > we will keep the common define.
> > 
> > Actually I think it would be possible and reasonable to use SI
> > units
> > in this case, since you are the vendor and have the resistor values
> > to implement the support. Having different sets of values for
> > different
> > chips is nothing out of the ordinary. We already have to account
> > for
> > different number of pins and different pin functions. That is what
> > compatible strings are for.
> 
> I fully agree with Chen-Yu's analysis here.
> 
> Zhiyong can you make an attempt to use SI units (Ohms) and see
> what it will look like? I think it will look better for users and it
> will
> be less risk to make mistakes.
> 
> Yours,
> Linus Walleij

Hi Linus & chen-yu,

The rsel actual bias resistance of each setting is different in
different IC. For example, in mt8195, the rsel actual bias resistance
setting like as:
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_RSE
L_110:1.5k in PU, 75k in PD;
MTK_PULL_SET_RSEL_111:1k in PU, 5k in PD.

but in mt8192, the rsel actual bias resistance setting like as:
MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD;
MTK_PULL_SET_RSEL_001:3k in PU, 5k in PD;
MTK_PULL_SET_RSEL_010:10k in PU, 75k in PD;
MTK_PULL_SET_RSEL_011:1k in PU, 5K in PD;

Can you help me to provide a suggestion common define for the all
different IC?
It seems that we should add a new define, if we upstream a new IC
pinctrl driver in the future.

Thanks.

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