linux-kernel - [PATCH 3.10 42/54] ARM: integrator: deactivate timer0 on the Integrator/CP

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Date:	Fri,  1 Nov 2013 15:04:10 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Rob Herring <rob.herring@...xeda.com>,
	Russell King <linux@....linux.org.uk>,
	Linus Walleij <linus.walleij@...aro.org>,
	Olof Johansson <olof@...om.net>
Subject: [PATCH 3.10 42/54] ARM: integrator: deactivate timer0 on the Integrator/CP

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Walleij <linus.walleij@...aro.org>

commit 29114fd7db2fc82a34da8340d29b8fa413e03dca upstream.

This fixes a long-standing Integrator/CP regression from
commit 870e2928cf3368ca9b06bc925d0027b0a56bcd8e
"ARM: integrator-cp: convert use CLKSRC_OF for timer init"

When this code was introduced, the both aliases pointing the
system to use timer1 as primary (clocksource) and timer2
as secondary (clockevent) was ignored, and the system would
simply use the first two timers found as clocksource and
clockevent.

However this made the system timeline accelerate by a
factor x25, as it turns out that the way the clocking
actually works (totally undocumented and found after some
trial-and-error) is that timer0 runs @ 25MHz and timer1
and timer2 runs @ 1MHz. Presumably this divider setting
is a boot-on default and configurable albeit the way to
configure it is not documented.

So as a quick fix to the problem, let's mark timer0 as
disabled, so the code will chose timer1 and timer2 as it
used to.

This also deletes the two aliases for the primary and
secondary timer as they have been superceded by the
auto-selection

Cc: Rob Herring <rob.herring@...xeda.com>
Cc: Russell King <linux@....linux.org.uk>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Olof Johansson <olof@...om.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm/boot/dts/integratorcp.dts |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/arch/arm/boot/dts/integratorcp.dts
+++ b/arch/arm/boot/dts/integratorcp.dts
@@ -9,11 +9,6 @@
 	model = "ARM Integrator/CP";
 	compatible = "arm,integrator-cp";
 
-	aliases {
-		arm,timer-primary = &timer2;
-		arm,timer-secondary = &timer1;
-	};
-
 	chosen {
 		bootargs = "root=/dev/ram0 console=ttyAMA0,38400n8 earlyprintk";
 	};
@@ -24,14 +19,18 @@
 	};
 
 	timer0: timer@...00000 {
+		/* TIMER0 runs @ 25MHz */
 		compatible = "arm,integrator-cp-timer";
+		status = "disabled";
 	};
 
 	timer1: timer@...00100 {
+		/* TIMER1 runs @ 1MHz */
 		compatible = "arm,integrator-cp-timer";
 	};
 
 	timer2: timer@...00200 {
+		/* TIMER2 runs @ 1MHz */
 		compatible = "arm,integrator-cp-timer";
 	};
 


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