linux-kernel - Re: [PATCH v4 7/9] serial: sc16is7xx: fix regression with GPIO configuration

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230531195723.462b140ac041b790711c1a7f@hugovil.com>
Date:   Wed, 31 May 2023 19:57:23 -0400
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     gregkh@...uxfoundation.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        jirislaby@...nel.org, jringle@...dpoint.com,
        l.perczak@...lintechnologies.com, tomasz.mon@...lingroup.com,
        linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: Re: [PATCH v4 7/9] serial: sc16is7xx: fix regression with GPIO
 configuration

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

> On Tue, May 30, 2023 at 6:36 PM Hugo Villeneuve <hugo@...ovil.com> wrote:
> > On Tue, 30 May 2023 01:38:17 +0300
> > andy.shevchenko@...il.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
>