linux-kernel - Re: [PATCH 2/2] pinctrl: pinctrl-npcm7xx: Set BGPIOF_VOLATILE

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Message-ID: <CAGMNF6VMLqRwVb=+-qU=nC9hW-idV-fLrnHFL9_xv7Ajha17og@mail.gmail.com>
Date:   Tue, 30 Oct 2018 22:06:52 -0700
From:   Kun Yi <kunyi@...gle.com>
To:     linus.walleij@...aro.org
Cc:     linux-gpio@...r.kernel.org, tmaimon77@...il.com,
        linux-kernel@...r.kernel.org, avifishman70@...il.com,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>, broonie@...nel.org
Subject: Re: [PATCH 2/2] pinctrl: pinctrl-npcm7xx: Set BGPIOF_VOLATILE_REG

On Tue, Oct 30, 2018 at 5:08 AM Linus Walleij <linus.walleij@...aro.org> wrote:
>
> On Wed, Oct 17, 2018 at 11:30 PM Kun Yi <kunyi@...gle.com> wrote:
>
> > Indicate that the pins are both controlled by the pinctrl driver and the
> > generic GPIO driver, thus GPIO driver should read the register value
> > before updating, instead of using the stored shadow register values.
> >
> > Signed-off-by: Kun Yi <kunyi@...gle.com>
>
> This is quite a rough measure, if we instead use regmap-mmio
> we can exercise fine control over what register are volatile and
> not instead of saying that all of them or some of them are.

Thanks for your review Linus! I don't have time to rewrite using
regmap-mmio at the moment though. I have discussed with the driver
author and we will first patch the pinctrl driver by making the
pinctrl functions use the gpio-mmio accessors instead of directly reg
read/writes. When I have time I will look into your suggestion to
improve the driver.

>
> Yours,
> Linus Walleij

-- 
Regards,
Kun