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Date: Tue, 23 Apr 2024 18:57:04 +0200
From: Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
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
Subject: Re: [PATCH v6 07/11] platform: cznic: turris-omnia-mcu: Add support
 for MCU provided TRNG
Message-ID: <20240423185704.2237bc65@thinkpad>
In-Reply-To: <CAHp75VcfmTeG+G1DkteR6GN96y3+h_Mz1YQ8U5asHJ7oTq+KbQ@mail.gmail.com>
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On Tue, 23 Apr 2024 19:43:41 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Tue, Apr 23, 2024 at 7:32=E2=80=AFPM Marek Beh=C3=BAn <kabel@kernel.or=
g> wrote:
> > On Tue, 23 Apr 2024 18:58:19 +0300
> > Andy Shevchenko <andy@kernel.org> wrote: =20
> > > On Thu, Apr 18, 2024 at 02:11:12PM +0200, Marek Beh=C3=BAn wrote: =20
>=20
> ...
>=20
> > > > +   irq_idx =3D omnia_int_to_gpio_idx[__bf_shf(INT_TRNG)];
> > > > +   irq =3D devm_irq_create_mapping(dev, mcu->gc.irq.domain, irq_id=
x);
> > > > +   if (irq < 0)
> > > > +           return dev_err_probe(dev, irq, "Cannot map TRNG IRQ\n")=
; =20
> > >
> > > This looks like some workaround against existing gpiod_to_irq(). Why =
do you
> > > need this? =20
> >
> > 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. =20
>=20
> Which one? GPIO has two: one per GPIO realm and one for IRQ domain.

The GPIO line validity is not enforced. The IRQ line validity is
enforced in the gpiochip_to_irq() method.

> > Is this semantically right to do even in spite of the fact that the
> > line is not a valid GPIO line? =20
>=20
> Yes. It's orthogonal to that.
>=20