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Date: Tue, 23 Apr 2024 20:25:14 +0300
From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Marek =?iso-8859-1?Q?Beh=FAn?= <kabel@kernel.org>
Cc: 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
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References: <20240418121116.22184-1-kabel@kernel.org>
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 <20240423183225.6e4f90a7@thinkpad>
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On Tue, Apr 23, 2024 at 06:57:04PM +0200, Marek Behún wrote:
> On Tue, 23 Apr 2024 19:43:41 +0300
> Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > On Tue, Apr 23, 2024 at 7:32 PM Marek Behún <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 Behún wrote:  

...

> > > > > +   irq_idx = omnia_int_to_gpio_idx[__bf_shf(INT_TRNG)];
> > > > > +   irq = 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 = 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.
> 
> The GPIO line validity is not enforced. The IRQ line validity is
> enforced in the gpiochip_to_irq() method.

Okay, but does it work for you as expected then?

If not, we should fix GPIO library to have gpiod_to_irq() to work as expected.

> > > 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.

-- 
With Best Regards,
Andy Shevchenko