linux-kernel - Re: (EXT) [PATCH] i2c: imx: add irqf_no

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Message-ID: <Yoi90G5cphagcxpp@shikoro>
Date:   Sat, 21 May 2022 12:24:16 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Alexander Stein <alexander.stein@...tq-group.com>
Cc:     Alifer Moraes <alifer.m@...iscite.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        eran.m@...iscite.com, festevam@...il.com, kernel@...gutronix.de,
        linux-imx@....com, linux-i2c@...r.kernel.org,
        linux@...pel-privat.de, pierluigi.p@...iscite.com,
        s.hauer@...gutronix.de, shawnguo@...nel.org,
        gaopan <b54642@...escale.com>,
        Fugang Duan <B38611@...escale.com>,
        Vipul Kumar <vipul_kumar@...tor.com>
Subject: Re: (EXT) [PATCH] i2c: imx: add irqf_no_suspend

Hi everyone,

> > The i2c irq is masked when pcie starts a i2c transfer process
> > during noirq suspend stage. As a result, i2c transfer fails.
> > To solve the problem, IRQF_NO_SUSPEND is added to i2c bus.
> > 
> > Signed-off-by: Gao Pan <b54642@...escale.com>
> > Signed-off-by: Fugang Duan <B38611@...escale.com>
> > Signed-off-by: Vipul Kumar <vipul_kumar@...tor.com>

The SoB from Alifer Moraes is missing, too.

> > goto rpm_disable;
> > 
> >  	/* Request IRQ */
> > -	ret = request_threaded_irq(irq, i2c_imx_isr, NULL, IRQF_SHARED,
> > +	ret = request_threaded_irq(irq, i2c_imx_isr, NULL,
> > +				   IRQF_SHARED | IRQF_NO_SUSPEND,
> >  				   pdev->name, i2c_imx);
> >  	if (ret) {
> >  		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
> 
> 
> I stumbled across Documentation/power/suspend-and-interrupts.rst which states:
> > For this reason, using IRQF_NO_SUSPEND and IRQF_SHARED at the
> > same time should be avoided.
> Given this IMHO at least a comment should be inserted why this is fine. I dont 
> have a full picture about the situation, but to me it seems there is a 
> reference missing, or why/how does some PCIe start some I2C transfer when the
> controller is suspended already? Do I miss something?

Thank you for this comment, Alexander. I second you, this needs
explanation.

Happy hacking,

   Wolfram


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