-----Original Message-----
From: Arnd Bergmann [mailto:arnd@kernel.org]
Sent: Saturday, February 13, 2021 9:23 AM
To: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Song Bao Hua (Barry Song) <redacted>; Andy Shevchenko
[off-list ref]; luojiaxing [off-list ref]; Linus
Walleij [off-list ref]; Santosh Shilimkar [off-list ref];
Kevin Hilman [off-list ref]; open list:GPIO SUBSYSTEM
[off-list ref]; linux-kernel@vger.kernel.org;
linuxarm@openeuler.org
Subject: Re: [Linuxarm] Re: [PATCH for next v1 1/2] gpio: omap: Replace
raw_spin_lock_irqsave with raw_spin_lock in omap_gpio_irq_handler()

On Fri, Feb 12, 2021 at 12:53 PM Grygorii Strashko
[off-list ref] wrote:

quoted

The worst RT case I can imagine is when gpio API is still called from hard

IRQ context by some

quoted

other device driver - some toggling for example.
Note. RT or "threadirqs" does not mean gpiochip become sleepable.

In this case:
  threaded handler
    raw_spin_lock
        IRQ from other device
           hard_irq handler
             gpiod_x()
                raw_spin_lock_irqsave() -- oops

Good point, I had missed the fact that drivers can call gpio functions from
hardirq context when I replied earlier, gpio is clearly special here.

Yes. Gpio provides APIs, thus, other drivers can go directly into the
territory of gpio driver.

Another one which is even more special might be m68k, which I cc-ed you
yesterday:
https://lore.kernel.org/lkml/c46ddb954cfe45d9849c911271d7ec23@hisilicon.com/ (local)

          Arnd

Thanks
Barry