linux-kernel - Re: [v2] gpio: dwapb: mask/unmask IRQ when disable/enale it

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Message-ID: <mdogxxro42ymeaykrgqpld2kqbppopbywcm76osskuf3df72sl@5jalt26vzcv4>
Date: Mon, 18 Dec 2023 15:07:45 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Andy Shevchenko <andy@...nel.org>
Cc: xiongxin <xiongxin@...inos.cn>, hoan@...amperecomputing.com, 
	linus.walleij@...aro.org, brgl@...ev.pl, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Riwen Lu <luriwen@...inos.cn>
Subject: Re: [v2] gpio: dwapb: mask/unmask IRQ when disable/enale it

On Mon, Dec 18, 2023 at 01:33:05PM +0200, Andy Shevchenko wrote:
> On Mon, Dec 18, 2023 at 04:12:46PM +0800, xiongxin wrote:
> > In the hardware implementation of the i2c hid driver based on dwapb gpio
> > irq, when the user continues to use the i2c hid device in the suspend
> > process, the i2c hid interrupt will be masked after the resume process
> > is finished.
> > 
> > This is because the disable_irq()/enable_irq() of the dwapb gpio driver
> > does not synchronize the irq mask register state. In normal use of the
> > i2c hid procedure, the gpio irq irq_mask()/irq_unmask() functions are
> > called in pairs. In case of an exception, i2c_hid_core_suspend() calls
> > disable_irq() to disable the gpio irq. With low probability, this causes
> > irq_unmask() to not be called, which causes the gpio irq to be masked
> > and not unmasked in enable_irq(), raising an exception.
> > 
> > Add synchronization to the masked register state in the
> > dwapb_irq_enable()/dwapb_irq_disable() function. mask the gpio irq
> > before disabling it. After enabling the gpio irq, unmask the irq.
> 
> > Fixes: 7779b3455697 ("gpio: add a driver for the Synopsys DesignWare APB GPIO block")
> > Signed-off-by: xiongxin <xiongxin@...inos.cn>
> 
> Your SoB should go last.
> 
> > Signed-off-by: Riwen Lu <luriwen@...inos.cn>
> 
> Then at all means what this SoB for? Either it's missing Co-developed-by,
> or simply wrong.
> 
> > Tested-by: xiongxin <xiongxin@...inos.cn>
> 
> This is assumed to be done by the contributor, but it's harmless to have it.
> 
> With the above being sorted out,
> Reviewed-by: Andy Shevchenko <andy@...nel.org>
> 
> ...
> 

> To Serge, I give my vote to hwirq as it is aligned with the documentation.

Right. Thanks for noting. It's now even more justified to use 'hwirq'
then.

-Serge(y)

> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>