linux-kernel - Re: [PATCH 10/10] ARM: dts: Fix dm814x pinctrl address and mask

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Message-ID: <20151202160955.GD23396@atomide.com>
Date:	Wed, 2 Dec 2015 08:09:56 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Matthijs van Duin <matthijsvanduin@...il.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Brian Hutchinson <b.hutchman@...il.com>,
	Delio Brignoli <dbrignoli@...ioscience.com>,
	Neil Armstrong <narmstrong@...libre.com>,
	Philipp Rosenberger <ilu@...utronix.de>
Subject: Re: [PATCH 10/10] ARM: dts: Fix dm814x pinctrl address and mask

* Tony Lindgren <tony@...mide.com> [151201 17:23]:
> * Matthijs van Duin <matthijsvanduin@...il.com> [151201 17:15]:
> > On 2 December 2015 at 01:46, Tony Lindgren <tony@...mide.com> wrote:
> > > Ouch. We should probably have separate PIN_INPUT_3V3 and PIN_OUTPUT_3V3
> > > dts macros that ensure that?
> > 
> > Can't we just keep bit 18 out of the function mask? The bootloader
> > should already have made sure all pins have bit 18 set (and bit 19 set
> > to correct values after ROM mucked them up, see advisory 2.1.88), so
> > all that needs to be done is avoid touching them.
> 
> Sounds good to me. And people who really want to override the mask can
> do it in the board specifc dts file.
> 
> > Are the power savings from disabling unnecessary inputs significant
> > enough to spend any headache on it?
> 
> Only for some battery powered devices, not in this case for sure.

And here's an updated version of this patch.

Regards,

Tony

8< ----------------------------
From: Tony Lindgren <tony@...mide.com>
Date: Tue, 1 Dec 2015 15:04:38 -0800
Subject: [PATCH] ARM: dts: Fix dm814x pinctrl address and mask

Otherwise pinctrl won't work. Because of silicon errata for some dm814x
versions, let's also keep bit 18 out of the function-mask and rely on
the bootloader configuration for bit 18  as suggested by
Matthijs van Duin <matthijsvanduin@...il.com>.

Devices with that need to use bit 18 can override the function-mask in
the board specific dts file if really needed.

Signed-off-by: Tony Lindgren <tony@...mide.com>

--- a/arch/arm/boot/dts/dm814x.dtsi
+++ b/arch/arm/boot/dts/dm814x.dtsi
@@ -205,13 +205,21 @@
 					};
 				};
 
+				/*
+				 * Note that silicon revision 2.1 and older
+				 * require input enabled (bit 18 set) for all
+				 * 3.3V I/Os to avoid cumulative hardware damage.
+				 * For more info, see errata advisory 2.1.87.
+				 * We leave bit 18 out of function-mask and rely
+				 * on the bootloader for it.
+				 */
 				pincntl: pinmux@800 {
 					compatible = "pinctrl-single";
-					reg = <0x800 0xc38>;
+					reg = <0x800 0x438>;
 					#address-cells = <1>;
 					#size-cells = <0>;
 					pinctrl-single,register-width = <32>;
-					pinctrl-single,function-mask = <0x300ff>;
+					pinctrl-single,function-mask = <0x307ff>;
 				};
 			};
 
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