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Date: Thu, 6 Jun 2024 10:53:08 +0200
From: Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>, Bartosz Golaszewski
 <brgl@bgdev.pl>
Cc: Gregory CLEMENT <gregory.clement@bootlin.com>, Arnd Bergmann
 <arnd@arndb.de>, soc@kernel.org, arm@kernel.org, Andy Shevchenko
 <andy@kernel.org>, Hans de Goede <hdegoede@redhat.com>, Ilpo
 =?UTF-8?B?SsOkcnZpbmVu?= <ilpo.jarvinen@linux.intel.com>, Olivia Mackall
 <olivia@selenic.com>, Herbert Xu <herbert@gondor.apana.org.au>, Greg
 Kroah-Hartman <gregkh@linuxfoundation.org>, linux-crypto@vger.kernel.org
Subject: Re: [PATCH v11 6/8] platform: cznic: turris-omnia-mcu: Add support
 for MCU provided TRNG
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On Wed, 5 Jun 2024 22:00:20 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> > +       irq_idx = omnia_int_to_gpio_idx[__bf_shf(OMNIA_INT_TRNG)];
> > +       irq = gpiod_to_irq(gpiochip_get_desc(&mcu->gc, irq_idx));
> > +       if (irq < 0)
> > +               return dev_err_probe(dev, irq, "Cannot get TRNG IRQ\n");  
> 
> Okay, it's a bit more complicated than that. The gpiochip_get_desc()
> shouldn't be used. Bart, what can you suggest to do here? Opencoding
> it doesn't sound to me a (fully) correct approach in a long term.

Note that I can't use gpiochip_request_own_desc(), nor any other
function that calls gpio_request_commit() (like gpiod_get()), because
that checks for gpiochip_line_is_valid(), and this returns false for
the TRNG line, cause that line is not a GPIO line, but interrupt only
line.

That is why I used
  irq = irq_create_mapping(dev, mcu->gc.irq.domain, irq_idx);
until v7, with no reference to gpio descriptors, since this line is not
a GPIO line.

We have discussed this back in April, in the thread
  https://lore.kernel.org/soc/20240418121116.22184-8-kabel@kernel.org/
where we concluded that
  irq = gpiod_to_irq(gpiochip_get_desc(gc, irq_idx));
is better...

Marek