From: Drew Fustini <drew@beagleboard.org>
To: Trent Piepho <tpiepho@gmail.com>
Cc: devicetree@vger.kernel.org,
Jason Kridner <jkridner@beagleboard.org>,
Tony Lindgren <tony@atomide.com>,
Linus Walleij <linus.walleij@linaro.org>,
linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
Rob Herring <robh+dt@kernel.org>,
Haojian Zhuang <haojian.zhuang@linaro.org>,
bcousson@baylibre.com, linux-omap@vger.kernel.org,
Robert Nelson <robertcnelson@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 1/2] pinctrl: single: parse #pinctrl-cells = 2
Date: Sun, 13 Sep 2020 21:42:33 +0200 [thread overview]
Message-ID: <20200913194233.GA1955808@x1> (raw)
In-Reply-To: <3139716.CMS8C0sQ7x@zen.local>
On Tue, Sep 08, 2020 at 04:52:58PM -0700, Trent Piepho wrote:
> On Tuesday, June 30, 2020 6:33:19 PM PDT Drew Fustini wrote:
> > If "pinctrl-single,pins" has 3 arguments (offset, conf, mux), then
> > pcs_parse_one_pinctrl_entry() does an OR operation on conf and mux to
> > get the value to store in the register.
>
>
> > - vals[found].val = pinctrl_spec.args[1];
> > +
> > + switch (pinctrl_spec.args_count) {
> > + case 2:
> > + vals[found].val = pinctrl_spec.args[1];
> > + break;
> > + case 3:
> > + vals[found].val = (pinctrl_spec.args[1] |
> pinctrl_spec.args[2]);
> > + break;
> > + }
> >
> > dev_dbg(pcs->dev, "%pOFn index: 0x%x value: 0x%x\n",
> > pinctrl_spec.np, offset,
> pinctrl_spec.args[1]);
>
> If #pinctrl-cells value is greater than 2, nothing will set vals[found].val to
> anything other than zero (from when it's calloc'ed) and the pinctrl will
> silently be programmed to zero.
If #pinctrl-cells is 3, then it will be:
vals[found].val = (pinctrl_spec.args[1] | pinctrl_spec.args[2]);
Do you mean if #pinctrl-cells is great than 3 then it will just have a
default value of zero?
That does appear to be the case and is probably not the behavior we
want. Thank you for pointing this out. Earlier, there is a check to
make sure there are at least 2 arguments:
if (pinctrl_spec.args_count < 2) {
dev_err(pcs->dev, "invalid args_count for spec: %i\n",
pinctrl_spec.args_count);
break;
}
I'll submit a patch where the upper bound is also checked:
if (pinctrl_spec.args_count < 2 || pinctrl_spec.args_count > 3) {
dev_err(pcs->dev, "invalid args_count for spec: %i\n",
pinctrl_spec.args_count);
break;
}
> The debug printout was not change to print vals[found].val, so it will
> continue to print the value of the 2nd cell.
Thank you for pointing this out. Yes, this is an oversight and I will
submit a patch.
> The result is that a #pinctrl-cells of 3 will produce no warning or error,
> program the pinctrl to zero, whilst at the same time emit debug log messages
> that it is programming the expected values.
>
> The device tree documentation still states that #pinctrl-cells must be 1 when
> using pinctrl-single,pins. This new special case of ORing two values is not
> documented.
This is a good point, too. I will make a patch to update the
documentation.
-Drew
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next prev parent reply other threads:[~2020-09-13 19:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 1:33 [PATCH v4 0/2] pinctrl: single: support #pinctrl-cells = 2 Drew Fustini
2020-07-01 1:33 ` [PATCH v4 1/2] pinctrl: single: parse " Drew Fustini
2020-09-08 23:52 ` Trent Piepho
2020-09-13 19:42 ` Drew Fustini [this message]
2020-09-13 23:27 ` Drew Fustini
2020-07-01 1:33 ` [PATCH v4 2/2] ARM: dts: am33xx-l4: change #pinctrl-cells from 1 to 2 Drew Fustini
2020-09-09 0:34 ` Trent Piepho
2021-01-15 18:02 ` Emmanuel Vadot
2021-01-15 21:40 ` Drew Fustini
2021-01-18 7:41 ` Tony Lindgren
2020-07-02 17:36 ` [PATCH v4 0/2] pinctrl: single: support #pinctrl-cells = 2 Tony Lindgren
2020-07-05 9:01 ` Haojian Zhuang
2020-07-07 10:59 ` Linus Walleij
2020-07-07 11:02 ` Drew Fustini
2020-07-11 21:12 ` Linus Walleij
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