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Date: Mon, 16 Mar 2020 15:42:21 +0100 From: Michał Mirosław <mirq-linux@...e.qmqm.pl> To: Dmitry Osipenko <digetx@...il.com> Cc: Ludovic Desroches <ludovic.desroches@...rochip.com>, Nicolas Ferre <nicolas.ferre@...rochip.com>, Alexandre Belloni <alexandre.belloni@...tlin.com>, linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] i2c: at91: support atomic write xfer On Sun, Mar 15, 2020 at 11:46:33PM +0300, Dmitry Osipenko wrote: > 15.03.2020 21:27, Michał Mirosław пишет: > > Implement basic support for atomic write - enough to get a simple > > write to PMIC on shutdown. Only for chips having ALT_CMD register, > > eg. SAMA5D2. > > > > Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl> > > --- > > Hello Michał, > > ... > > + ret = pm_runtime_get_sync(dev->dev); > > + if (ret < 0) > > + goto out; > > Runtime PM can't be used while interrupts are disabled, unless > pm_runtime_irq_safe() is used and driver's RPM callback is IRQ-safe. I didn't get any warnings from lockdep and friends, but I'll double check if this is by luck. > ... > > + timeout = jiffies + (2 + msg->len) * HZ/1000; > > + for (;;) { > > + stat = at91_twi_read(dev, AT91_TWI_SR); > > + if (stat & AT91_TWI_TXCOMP) > > + break; > > + if (time_after(jiffies, timeout)) { > > + ret = -ETIMEDOUT; > > + goto out; > > + } > > + udelay(100); > > + } > > Jiffies can't be used with the disabled interrupts because jiffies are > updated by timer's interrupt. > > Either ktime() API or iterator-based loop should be used. Thanks for the pointers. In my use-case power is cut from the CPU at this point so it didn't matter that the loop was infinite. Best Regards Michał Mirosław
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