linux-kernel - Re: [PATCH] pinctrl: aspeed: Force to disable the function's signal

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Message-ID: <CACRpkdZSw9Nn8hp+C3SPw4_EkXn0mkLh8tSO5zhGR8xdv=Jk8g@mail.gmail.com>
Date:   Wed, 31 Aug 2022 14:15:04 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Billy Tsai <billy_tsai@...eedtech.com>
Cc:     andrew@...id.au, joel@....id.au, linux-aspeed@...ts.ozlabs.org,
        openbmc@...ts.ozlabs.org, linux-gpio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl: aspeed: Force to disable the function's signal

On Thu, Aug 18, 2022 at 12:18 PM Billy Tsai <billy_tsai@...eedtech.com> wrote:

> When the driver want to disable the signal of the function, it doesn't
> need to query the state of the mux function's signal on a pin. The
> condition below will miss the disable of the signal:
> Ball | Default | P0 Signal | P0 Expression               | Other
> -----+---------+-----------+-----------------------------+----------
>  E21   GPIOG0    SD2CLK      SCU4B4[16]=1 & SCU450[1]=1    GPIOG0
> -----+---------+-----------+-----------------------------+----------
>  B22   GPIOG1    SD2CMD      SCU4B4[17]=1 & SCU450[1]=1    GPIOG1
> -----+---------+-----------+-----------------------------+----------
> Assume the register status like below:
> SCU4B4[16] == 1 & SCU4B4[17] == 1 & SCU450[1]==1
> After the driver set the Ball E21 to the GPIOG0:
> SCU4B4[16] == 0 & SCU4B4[17] == 1 & SCU450[1]==0
> When the driver want to set the Ball B22 to the GPIOG1, the condition of
> the SD2CMD will be false causing SCU4B4[17] not to be cleared.
>
> Signed-off-by: Billy Tsai <billy_tsai@...eedtech.com>

Patch applied!

Yours,
Linus Walleij