linux-kernel - Re: [PATCH] pinctrl: rockchip: enable clock when reading pin direction register

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Message-ID: <2334693.oO4CeGnqou@phil>
Date:   Tue, 12 Dec 2017 19:19:19 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH] pinctrl: rockchip: enable clock when reading pin direction register

Hi Brian,

Am Dienstag, 12. Dezember 2017, 09:43:43 CET schrieb Brian Norris:
> We generally leave the GPIO clock disabled, unless an interrupt is
> requested or we're accessing IO registers. We forgot to do this for the
> ->get_direction() callback, which means we can sometimes [1] get
> incorrect results [2] from, e.g., /sys/kernel/debug/gpio.
> 
> Enable the clock, so we get the right results!
> 
> [1] Sometimes, because many systems have 1 or mor interrupt requested on
> each GPIO bank, so they always leave their clock on.
> 
> [2] Incorrect, meaning the register returns 0, and so we interpret that
> as "input".
> 
> Signed-off-by: Brian Norris <briannorris@...omium.org>

thanks for catching this and it looks good to me, so
Reviewed-by: Heiko Stuebner <heiko@...ech.de>