linux-kernel - Re: [PATCH v6] rtc: pcf2127: handle timestamp interrupts

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Date:   Mon, 5 Jul 2021 14:13:55 +0200
From:   Mian Yousaf Kaukab <ykaukab@...e.de>
To:     Bruno Thomsen <bruno.thomsen@...il.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-rtc@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>, biwen.li@....com
Subject: Re: [PATCH v6] rtc: pcf2127: handle timestamp interrupts

On Wed, Jun 30, 2021 at 08:26:04PM +0200, Bruno Thomsen wrote:
> Den tir. 29. jun. 2021 kl. 17.06 skrev Mian Yousaf Kaukab <ykaukab@...e.de>:
> >
> > commit 03623b4b041c ("rtc: pcf2127: add tamper detection support")
> > added support for timestamp interrupts. However they are not being
> > handled in the irq handler. If a timestamp interrupt occurs it
> > results in kernel disabling the interrupt and displaying the call
> > trace:
> >
> > [  121.145580] irq 78: nobody cared (try booting with the "irqpoll" option)
> > ...
> > [  121.238087] [<00000000c4d69393>] irq_default_primary_handler threaded [<000000000a90d25b>] pcf2127_rtc_irq [rtc_pcf2127]
> > [  121.248971] Disabling IRQ #78
> >
> > Handle timestamp interrupts in pcf2127_rtc_irq(). Save time stamp
> > before clearing TSF1 and TSF2 flags so that it can't be overwritten.
> > Set a flag to mark if the timestamp is valid and only report to sysfs
> > if the flag is set. To mimic the hardware behavior, don’t save
> > another timestamp until the first one has been read by the userspace.
> >
> > However, if the alarm irq is not configured, keep the old way of
> > handling timestamp interrupt in the timestamp0 sysfs calls.
> >
> > Signed-off-by: Mian Yousaf Kaukab <ykaukab@...e.de>
> > ---
> > Sorry, once again compile tested only due to lack of hardware
> > availability. Hopefully, I will be able to do some real tests tomorrow.
> 
> Hi Yousaf,
> 
> I have tested patch version 6 on an imx7 board with the pcf2127
> chip using SPI interface and no alarm IRQ in the device tree.
> The same board that produced an oops earlier, and now it's working
> as expected. Both tamper events that occur when the device is
> powered on and when an event happens with the device powered off.
> 
> Reviewed-by: Bruno Thomsen <bruno.thomsen@...il.com>
> Tested-by: Bruno Thomsen <bruno.thomsen@...il.com>
Thank you for reviewing and testing the patch!
I have tested it with alarm irq configured and it works fine.

Alexandre, is it still possible to queue for v5.14?
> 
> /Bruno
> 
BR,
Yousaf