linux-kernel - Re: [PATCH v4] rtc: pcf2127: handle timestamp interrupts

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Date:   Thu, 27 May 2021 16:23:36 +0200
From:   Mian Yousaf Kaukab <ykaukab@...e.de>
To:     a.zummo@...ertech.it, alexandre.belloni@...tlin.com
Cc:     linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org,
        biwen.li@....com
Subject: Re: [PATCH v4] rtc: pcf2127: handle timestamp interrupts

On Tue, May 25, 2021 at 12:11:07PM +0200, Mian Yousaf Kaukab wrote:
> 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.
Alexandre, I hope this patch addresses all your concerns. Please let
me know if thats not the case.

BR,
Yousaf