linux-kernel - Re: [PATCH 2/7] pinctrl: mediatek: paris: Fix PIN_CONFIG_BIAS

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Date:   Thu, 20 Jan 2022 09:47:00 +0800
From:   Guodong Liu <guodong.liu@...iatek.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
CC:     Sean Wang <sean.wang@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-mediatek@...ts.infradead.org>, <linux-gpio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Zhiyong Tao <zhiyong.tao@...iatek.com>,
        Hui Liu <hui.liu@...iatek.com>,
        Light Hsieh <light.hsieh@...iatek.com>
Subject: Re: [PATCH 2/7] pinctrl: mediatek: paris: Fix
 PIN_CONFIG_BIAS_DISABLE readback

-----Original Message-----
From: Chen-Yu Tsai <wenst@...omium.org>
To: Guodong Liu <guodong.liu@...iatek.com>
Cc: Sean Wang <sean.wang@...nel.org>, Linus Walleij <
linus.walleij@...aro.org>, Matthias Brugger <matthias.bgg@...il.com>, 
linux-mediatek@...ts.infradead.org, linux-gpio@...r.kernel.org, 
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Zhiyong Tao <zhiyong.tao@...iatek.com>, Hui Liu <hui.liu@...iatek.com>,
Light Hsieh <light.hsieh@...iatek.com>
Subject: Re: [PATCH 2/7] pinctrl: mediatek: paris: Fix
PIN_CONFIG_BIAS_DISABLE readback
Date: Wed, 19 Jan 2022 13:57:18 +0800

On Wed, Jan 19, 2022 at 9:42 AM Guodong Liu <guodong.liu@...iatek.com>
wrote:
> 
> -----Original Message-----
> From: Chen-Yu Tsai <wenst@...omium.org>
> To: Sean Wang <sean.wang@...nel.org>, Linus Walleij <
> linus.walleij@...aro.org>, Matthias Brugger <matthias.bgg@...il.com>
> Cc: Chen-Yu Tsai <wenst@...omium.org>,
> linux-mediatek@...ts.infradead.org, linux-gpio@...r.kernel.org,
> linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
> Zhiyong Tao <zhiyong.tao@...iatek.com>, Guodong Liu <
> guodong.liu@...iatek.com>
> Subject: [PATCH 2/7] pinctrl: mediatek: paris: Fix
> PIN_CONFIG_BIAS_DISABLE readback
> Date: Tue, 11 Jan 2022 19:22:39 +0800
> 
> When reading back pin bias settings, if the pin is not in a
> bias-disabled state, the function should return -EINVAL.
> 
> Fix this in the mediatek-paris pinctrl library so that the read back
> state is not littered with bogus a "input bias disabled" combined
> with
> "pull up" or "pull down" states.
> 
> Fixes: 805250982bb5 ("pinctrl: mediatek: add pinctrl-paris that
> implements the vendor dt-bindings")
> Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> ---
>  drivers/pinctrl/mediatek/pinctrl-paris.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pinctrl/mediatek/pinctrl-paris.c
> b/drivers/pinctrl/mediatek/pinctrl-paris.c
> index f9f9110f2107..1ca598ea7ba7 100644
> --- a/drivers/pinctrl/mediatek/pinctrl-paris.c
> +++ b/drivers/pinctrl/mediatek/pinctrl-paris.c
> @@ -97,8 +97,8 @@ static int mtk_pinconf_get(struct pinctrl_dev
> *pctldev,
>                         if (err)
>                                 goto out;
>                         if (param == PIN_CONFIG_BIAS_DISABLE) {
> -                               if (ret == MTK_PUPD_SET_R1R0_00)
> -                                       ret = MTK_DISABLE;
> +                               if (ret != MTK_PUPD_SET_R1R0_00)
> +                                       err = -EINVAL;
> Hi Chen-Yu
> 
> When the API "hw->soc->bias_get_combo(hw, desc, &pullup, &ret)" is
> called,
> The ret vaule of ret may be MTK_DISABLE or MTK_PUPD_SET_R1R0_00
> or  (pullen
> == 0),  All those cases are expected to be as "bias-disable".
> We advices to keep original code,
> +                               if (ret == MTK_PUPD_SET_R1R0_00)
> +                                       ret = MTK_DISABLE;
> +                               if (ret != MTK_DISABLE)
> +                                       err = -EINVAL;

IIUC you are suggesting to assign MTK_DISABLE to ret in the other two
cases,
and then check if ret == MTK_DISABLE.

Thanks for pointing that out.

ChenYu

> Thanks

Hi Chen-Yu

Yes, just for pins with config of MTK_PUPD_SET_R1R0_00 are required to
do additional assignment operations(ret = MTK_DISABLE;), in the other
two cases, the assignment operations of ret as MTK_DISABLE is obtained
by function call "hw->soc->bias_get_combo(hw, desc, &pullup, &ret)".

Thanks

>                         } else if (param == PIN_CONFIG_BIAS_PULL_UP)
> {
>                                 /* When desire to get pull-up value,
> return
>                                  *  error if current setting is pull-
> down
>