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Date:   Wed, 31 May 2023 19:57:23 -0400
From:   Hugo Villeneuve <hugo@hugovil.com>
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     gregkh@linuxfoundation.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
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        linux-serial@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
        Hugo Villeneuve <hvilleneuve@dimonoff.com>
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Subject: Re: [PATCH v4 7/9] serial: sc16is7xx: fix regression with GPIO
 configuration
Precedence: bulk

On Wed, 31 May 2023 00:56:57 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Tue, May 30, 2023 at 6:36 PM Hugo Villeneuve <hugo@hugovil.com> wrote:
> > On Tue, 30 May 2023 01:38:17 +0300
> > andy.shevchenko@gmail.com wrote:
> > > Mon, May 29, 2023 at 10:07:09AM -0400, Hugo Villeneuve kirjoitti:
> 
> ...
> 
> > > GENMASK()
> >
> > Ok done, altough even if in general I like the bit manipulation macros because they make the code easier to read/understand, I find it less obvious by using GENMASK in this case IMMO.
> 
> GENMASK() was introduced to increase code robustness:
> 1) to make sure the bits mentioned are correct
> 2) to check the bit boundary.
> 
> ...
> 
> > > > +           of_property_for_each_u32(dev->of_node, "nxp,modem-control-line-ports",
> > > > +                                    prop, p, u) {
> > > > +                   if (u >= devtype->nr_uart)
> > > > +                           continue;
> > > > +
> > > > +                   /* Use GPIO lines as modem control lines */
> > > > +                   if (u == 0)
> > > > +                           mctrl_mask |= SC16IS7XX_IOCONTROL_MODEM_A_BIT;
> > > > +                   else if (u == 1)
> > > > +                           mctrl_mask |= SC16IS7XX_IOCONTROL_MODEM_B_BIT;
> > > > +           }
> > >
> > > Can we use device properties, please?
> >
> > I have converted this section to use device_property_count_u32() and device_property_read_u32_array(). Is that Ok?
> 
> Yes, thank you!

Hi Andy,
now that I am using the device property API, I think I no longer have the need to test for "if (dev->of_node)" before reading the new property "nxp,modem-control-line-ports"?

If that is the case, I will leave the test "if (dev->of_node)" only for the "irda-mode-ports" property.

The pseudo code woulk look like this:

	if (dev->of_node) {
		struct property *prop;
		const __be32 *p;
		u32 u;

		of_property_for_each_u32(dev->of_node, "irda-mode-ports",
					 prop, p, u)
			if (u < devtype->nr_uart)
				s->p[u].irda_mode = true;
	}

        /* Read "nxp,modem-control-line-ports" using device property API. */
	sc16is7xx_setup_mctrl_ports(dev);

Thank you,
Hugo.


> > > If you think about backporting to the earlier kernels (w/o properties in use in
> > > this driver), perhaps an additional followup for that?
> >
> > I am not sure what you mean by this?
> 
> If the device property API was not yet available for this fix being
> backported to the old enough kernel we have to use old OF stuff. In
> that case the device property conversion needs to be done in a
> separate change.
> 
> -- 
> With Best Regards,
> Andy Shevchenko
>