Re: [PATCH v2 08/14] gpio: dwapb: Convert to use IRQ core provided macros

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

On Wed, Apr 15, 2020 at 08:53:09PM +0300, Serge Semin wrote:
> On Wed, Apr 15, 2020 at 05:15:28PM +0300, Andy Shevchenko wrote:
> > IRQ core provides macros such as IRQ_RETVAL().
> > Convert code to use them.

> BTW Forgot to mention. Irrelevantly to this patch just so you know seeing
> you are from Intel and this part is being utilized by the Intel Quark SoC.
> dwapb_irq_handler_mfd() handler will cause a problem in RT-patched kernel
> (I've seen such issue in another GPIO-driver). So if PREEMP_RT_FULL patch
> is applied and the FULL-RT scheduler is enabled all interrupt handlers
> specified by request_irq()-based methods will be handled by a kernel thread,
> while generic_handle_irq() is supposed to be called from the atomic context
> only (with interrupts disabled). As a result an ugly stack dump will be printed
> to the kernel log by the next code:
> https://elixir.bootlin.com/linux/latest/source/kernel/irq/handle.c#L152
> 
> A way to fix this is described in Documentation/driver-api/gpio/driver.rst

There is patch from Siemens to fix that [1]. I dunno if they are going to upstream it.
Jan?

[1]: https://github.com/siemens/meta-iot2000/blob/master/meta-iot2000-bsp/recipes-kernel/linux/patches/rt-0002-gpio-dwapb-Work-around-RT-full-s-enforced-IRQ-thread.patch

-- 
With Best Regards,
Andy Shevchenko