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References: <20240418121116.22184-1-kabel@kernel.org> <20240418121116.22184-8-kabel@kernel.org>
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From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Tue, 23 Apr 2024 19:43:41 +0300
Message-ID: <CAHp75VcfmTeG+G1DkteR6GN96y3+h_Mz1YQ8U5asHJ7oTq+KbQ@mail.gmail.com>
Subject: Re: [PATCH v6 07/11] platform: cznic: turris-omnia-mcu: Add support
 for MCU provided TRNG
To: =?UTF-8?B?TWFyZWsgQmVow7pu?= <kabel@kernel.org>
Cc: Andy Shevchenko <andy@kernel.org>, Gregory CLEMENT <gregory.clement@bootlin.com>, 
	Arnd Bergmann <arnd@arndb.de>, soc@kernel.org, Olivia Mackall <olivia@selenic.com>, 
	Herbert Xu <herbert@gondor.apana.org.au>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-crypto@vger.kernel.org, arm@kernel.org
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On Tue, Apr 23, 2024 at 7:32=E2=80=AFPM Marek Beh=C3=BAn <kabel@kernel.org>=
 wrote:
> On Tue, 23 Apr 2024 18:58:19 +0300
> Andy Shevchenko <andy@kernel.org> wrote:
> > On Thu, Apr 18, 2024 at 02:11:12PM +0200, Marek Beh=C3=BAn wrote:

...

> > > +   irq_idx =3D omnia_int_to_gpio_idx[__bf_shf(INT_TRNG)];
> > > +   irq =3D devm_irq_create_mapping(dev, mcu->gc.irq.domain, irq_idx)=
;
> > > +   if (irq < 0)
> > > +           return dev_err_probe(dev, irq, "Cannot map TRNG IRQ\n");
> >
> > This looks like some workaround against existing gpiod_to_irq(). Why do=
 you
> > need this?
>
> Hmmm, I thought that would not work because that line is only valid
> as an IRQ, not as a GPIO (this is enforced via the valid_mask member of
> gpio_chip and gpio_irq_chip).
>
> But looking at the code of gpiolib, if I do
>   irq =3D gpiod_to_irq(gpiochip_get_desc(gc, irq_idx));
> the valid_mask is not enforced anywhere.

Which one? GPIO has two: one per GPIO realm and one for IRQ domain.

> Is this semantically right to do even in spite of the fact that the
> line is not a valid GPIO line?

Yes. It's orthogonal to that.

--=20
With Best Regards,
Andy Shevchenko