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Date: Mon, 20 Jun 2022 13:29:30 +0000 From: Pierluigi Passaro <pierluigi.p@...iscite.com> To: Wolfram Sang <wsa@...nel.org>, Alexander Stein <alexander.stein@...tq-group.com> CC: Alifer Willians de Moraes <alifer.m@...iscite.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, Eran Matityahu <eran.m@...iscite.com>, "festevam@...il.com" <festevam@...il.com>, "kernel@...gutronix.de" <kernel@...gutronix.de>, "linux-imx@....com" <linux-imx@....com>, "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>, "linux@...pel-privat.de" <linux@...pel-privat.de>, "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "shawnguo@...nel.org" <shawnguo@...nel.org>, gaopan <b54642@...escale.com>, Fugang Duan <B38611@...escale.com>, Vipul Kumar <vipul_kumar@...tor.com> Subject: Re: [PATCH] i2c: imx: add irqf_no_suspend Hi All, > 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? This patch has been introduced to fix the following behavior. HW conditions - Variscite DART-MX8M on DT8MCustomBoard v2.x or higher. - The PCIe connector uses a reset pin coming from a GPIO expander connected to the I2C bus. SW behavior - Upon wake-up, the PCIe try toggling the reset pins, but the GPIO expander / I2C bus are still suspended, leading to a PCIe wake-up failure. >From our investigation, we can't identify a way to postpone PCIe wake-up after I2C wake-up. This patch is still present in latest NXP kernel 5.15, but please let me know if you think this should be approached / fixed in a different way. Thanks Regards Pier > Thank you for this comment, Alexander. I second you, this needs > explanation. > Happy hacking, > Wolfram
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