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

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Message-ID: <8564532.G8NNa9Oa4k@phil>
Date:   Wed, 15 Mar 2017 19:16:53 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     John Keeping <john@...anate.com>
Cc:     Julia Cartwright <julia@...com>,
        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

Am Mittwoch, 15. März 2017, 18:08:06 CET schrieb John Keeping:
> 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.

That part could very well also use regmap_update_bits like the other parts.
Not really sure, why we use regmap_write here, but I'm also not sure, if it 
matters at all.