linux-kernel - Re: [PATCH v5] Fix freeze in lm8333 i2c keyboard driver

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Message-ID: <ZF19yOojiaSbo3vS@google.com>
Date:   Thu, 11 May 2023 16:44:08 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Jeff LaBundy <jeff@...undy.com>
Cc:     Tomas Mudrunka <tomas.mudrunka@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] Fix freeze in lm8333 i2c keyboard driver

On Wed, May 03, 2023 at 08:44:06PM -0500, Jeff LaBundy wrote:
> Hi Tomas,
> 
> On Wed, May 03, 2023 at 05:32:31PM +0200, Tomas Mudrunka wrote:
> > LM8333 uses gpio interrupt line which is triggered by falling edge.
> > When button is pressed before driver is loaded,
> > driver will miss the edge and never respond again.
> > To fix this we run the interrupt handler before registering IRQ
> > to clear the interrupt via i2c command.
> > 
> > Signed-off-by: Tomas Mudrunka <tomas.mudrunka@...il.com>
> > ---
> 
> Reviewed-by: Jeff LaBundy <jeff@...undy.com>
> 
> >  drivers/input/keyboard/lm8333.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/input/keyboard/lm8333.c b/drivers/input/keyboard/lm8333.c
> > index 7457c3220..52108c370 100644
> > --- a/drivers/input/keyboard/lm8333.c
> > +++ b/drivers/input/keyboard/lm8333.c
> > @@ -178,6 +178,8 @@ static int lm8333_probe(struct i2c_client *client)
> >  			dev_warn(&client->dev, "Unable to set active time\n");
> >  	}
> >  
> > +	lm8333_irq_thread(client->irq, lm8333);

So this is still racy, isn't it? The interrupt may come after read is
done, but before we register the handler.

> > +
> >  	err = request_threaded_irq(client->irq, NULL, lm8333_irq_thread,
> >  				   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> >  				   "lm8333", lm8333);
> > -- 
> > 2.40.1
> 

Thanks.

-- 
Dmitry