linux-kernel - Re: [PATCH v1 2/2] pinctrl: rockchip: only enable gpio clock when it setting

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Date:	Mon, 3 Aug 2015 13:21:27 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	huang lin <hl@...k-chips.com>
Cc:	Heiko Stübner <heiko@...ech.de>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/2] pinctrl: rockchip: only enable gpio clock when it setting

hl

On Sun, Aug 2, 2015 at 8:56 PM, huang lin <hl@...k-chips.com> wrote:
> gpio can keep state even the clock disable, for save power
> consumption, only enable gpio clock when it setting
>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> Signed-off-by: huang lin <hl@...k-chips.com>
>
> Signed-off-by: huang lin <hl@...k-chips.com>

Your "Signed-off-by"s are a little wonky here...  Can you fix up?

> ---
>  drivers/pinctrl/pinctrl-rockchip.c | 60 ++++++++++++++++++++++++++++++++++----
>  1 file changed, 54 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pinctrl/pinctrl-rockchip.c b/drivers/pinctrl/pinctrl-rockchip.c
> index cc2843a..445829f 100644
> --- a/drivers/pinctrl/pinctrl-rockchip.c
> +++ b/drivers/pinctrl/pinctrl-rockchip.c
> @@ -945,17 +945,20 @@ static int _rockchip_pmx_gpio_set_direction(struct gpio_chip *chip,
>         if (ret < 0)
>                 return ret;
>
> +       clk_enable(bank->clk);
>         spin_lock_irqsave(&bank->slock, flags);
>
> -       data = readl_relaxed(bank->reg_base + GPIO_SWPORT_DDR);
> +       data = readl(bank->reg_base + GPIO_SWPORT_DDR);

I am a little curious why you need to change the readl_relaxed() to a
read().  Are you trying to ensure that the clock was on before the
read happened?  If so, I think this won't help.  I see:

#define readl(c) ({ u32 __v = readl_relaxed(c); __iormb(); __v; })

...so that means that the iormb() is _after_ the readl.

...but I would believe that the clk_enable() call itself would be
guaranteeing that the clock was enabled in time.  ...and if not then
grabbing the spinlock is another barrier, right?  I think you do this
in a few places...

Other than that this patch looks good to me....

-Doug
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