linux-kernel - Re: [PATCH v2 2/4] pinctrl: rockchip: convert to raw spinlock

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Message-ID: <20170315180806.3714af56.john@metanate.com>
Date:   Wed, 15 Mar 2017 18:08:06 +0000
From:   John Keeping <john@...anate.com>
To:     Julia Cartwright <julia@...com>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        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>
Subject: Re: [PATCH v2 2/4] pinctrl: rockchip: convert to raw spinlock

On Wed, 15 Mar 2017 13:01:37 -0500, Julia Cartwright wrote:
> On Wed, Mar 15, 2017 at 05:46:52PM +0000, John Keeping wrote:
> > This lock is used from rockchip_irq_set_type() which is part of the
> > irq_chip implementation and thus must use raw_spinlock_t as documented
> > in Documentation/gpio/driver.txt.
> > 
> > Signed-off-by: John Keeping <john@...anate.com>
> > Reviewed-by: Heiko Stuebner <heiko@...ech.de>
> > Tested-by: Heiko Stuebner <heiko@...ech.de>
> > ---
> > v2: unchanged
> > ---
> >  drivers/pinctrl/pinctrl-rockchip.c | 30 +++++++++++++++---------------
> >  1 file changed, 15 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/pinctrl/pinctrl-rockchip.c b/drivers/pinctrl/pinctrl-rockchip.c
> > index 128c383ea7ba..8c1cae6d78d7 100644
> > --- a/drivers/pinctrl/pinctrl-rockchip.c
> > +++ b/drivers/pinctrl/pinctrl-rockchip.c
> > @@ -163,7 +163,7 @@ struct rockchip_pin_bank {
> >  	struct irq_domain		*domain;
> >  	struct gpio_chip		gpio_chip;
> >  	struct pinctrl_gpio_range	grange;
> > -	spinlock_t			slock;
> > +	raw_spinlock_t			slock;
> >  	u32				toggle_edge_mode;
> >  };
> >  
> > @@ -1295,14 +1295,14 @@ static int rockchip_set_pull(struct rockchip_pin_bank *bank,
> >  
> >  	switch (ctrl->type) {
> >  	case RK2928:
> > -		spin_lock_irqsave(&bank->slock, flags);
> > +		raw_spin_lock_irqsave(&bank->slock, flags);
> >  
> >  		data = BIT(bit + 16);
> >  		if (pull == PIN_CONFIG_BIAS_DISABLE)
> >  			data |= BIT(bit);  
> 
> This should be lifted out from under the lock.
> 
> >  		ret = regmap_write(regmap, reg, data);  
> 
> How is this legal?  The regmap_write() here is going to end up acquiring
> the regmap mutex.

It's not, the spinlock can be deleted here.  I only have RK3288 hardware
to test and I missed this when checking the uses of slock.


John