linux-kernel - Re: [PATCH v2 1/2] iio: Improve the kernel-doc of iio_trigger

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Message-ID: <ZADMRsDgxKZ/UfJj@carbian>
Date:   Thu, 2 Mar 2023 17:18:14 +0100
From:   Mehdi Djait <mehdi.djait.k@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     jic23@...nel.org, lars@...afoo.de, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] iio: Improve the kernel-doc of iio_trigger_poll

Hello Andy,

On Thu, Mar 02, 2023 at 05:54:05PM +0200, Andy Shevchenko wrote:
> On Thu, Mar 02, 2023 at 02:04:35PM +0100, Mehdi Djait wrote:
> > Move the kernel-doc of the function to industrialio-trigger.c
> > Add a note on the context where the function is expected to be called.
> 
> ...
> 
> > v2:
> > - Changed the expected context of from interrupt to hard IRQ context
> 
> Thank you for an update.
> 
> But it seems I messed up with this and my previous remark shouldn't be
> taken into consideration.
> 
> The "relevant hardware interrupt handler" may be hard and threaded IRQ context,
> which looks like your first version was correct.
> 
> Let's wait for Jonathan opinion on this as he is a native speaker.

If I understood the function correctly I think you were right. It should
be hard IRQ context

The relevant functions calls:
iio_trigger_poll --> generic_handle_irq --> handle_irq_desc

handle_irq_desc: returns Operation not permitted if !in_hardirq() && handle_enforce_irqctx 
and it is the reason why the sysfs trigger uses the irq_framework to call iio_trigger_poll 
from hard IRQ context [1][2]

[1] https://lwn.net/Articles/411605/ 
[2] https://lore.kernel.org/all/1346922337-17088-1-git-send-email-lars@metafoo.de/

--
Kind Regards
Mehdi Djait