linux-kernel - Re: [PATCH] pinctrl: rockchip: don't disable clk when irq mask is already set

Open Source and information security mailing list archives

Date:   Tue, 27 Sep 2016 00:35:18 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Shawn Lin <shawn.lin@...k-chips.com>
Cc:     Jacob Chen <jacob-chen@...wrt.com>, linux-kernel@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linus.walleij@...aro.org,
        Jacob Chen <jacob2.chen@...k-chips.com>,
        linux-gpio@...r.kernel.org
Subject: Re: [PATCH] pinctrl: rockchip: don't disable clk when irq mask is already set

Am Samstag, 24. September 2016, 18:24:11 CEST schrieb Shawn Lin:
> On 2016/9/24 2:26, Jacob Chen wrote:
> > From: Jacob Chen <jacob2.chen@...k-chips.com>
> > 
> > In some drivers, disable_irq() call don't be symmetric with enable_irq()
> > , disable_irq() will be called before call free_irq().
> 
> Which upstream drivers you refer to?
> 
> Shouldn't it be the unbalanced call for these drivers?
> 
> > But both disable_irq() and free_irq() will call
> > rockchip_irq_gc_mask_set_bit,> 
> >  and clk_disable() will be called more times than clk_enable(), which will
> > 
> > cause bugs.
> > 
> > I think we can correct that by checking of mask.If mask is already set, do
> > nothing.
> Looks like a little hacky to me.

that may be true, but on first glance I tend to agree with Jacob.
Look for example at (a driver using disable_irq I picked at random) drivertc/
rtcrs/-tps6586x.c .

In its probe function it does devm_request_irq directly followed by 
disable_irq on its alarm interrupt. The interrupt only gets enabled again if 
the rtc alarm gets enabled. So you can easily run into the disable + free case 
there as well. Similar probably in a lot of other drivers.

Heiko

> 
> > Change-Id: If19912c7658253e15531c04db6c70fdbffd5960a
> 
> remove this.
> 
> > Signed-off-by: Jacob Chen <jacob2.chen@...k-chips.com>
> > ---
> > 
> >  drivers/pinctrl/pinctrl-rockchip.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/pinctrl/pinctrl-rockchip.c
> > b/drivers/pinctrl/pinctrl-rockchip.c index c6c04ac..9a8804a 100644
> > --- a/drivers/pinctrl/pinctrl-rockchip.c
> > +++ b/drivers/pinctrl/pinctrl-rockchip.c
> > @@ -2334,8 +2334,12 @@ static void rockchip_irq_gc_mask_clr_bit(struct
> > irq_data *d)> 
> >  void rockchip_irq_gc_mask_set_bit(struct irq_data *d)
> >  {
> >  
> >  	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
> > 
> > +	struct irq_chip_type *ct = irq_data_get_chip_type(d);
> > 
> >  	struct rockchip_pin_bank *bank = gc->private;
> > 
> > +	if (*ct->mask_cache & d->mask)
> > +		return;
> > +
> > 
> >  	irq_gc_mask_set_bit(d);
> >  	clk_disable(bank->clk);
> >  
> >  }
> > 
> > --
> > 2.7.4
> > 
> > 
> > _______________________________________________
> > Linux-rockchip mailing list
> > Linux-rockchip@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-rockchip

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