linux-kernel - [PATCH 3.16 006/114] ARM: OMAP2+: hwmod: Fix updating of sysconfig register

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Date:	Mon, 13 Jun 2016 19:36:37 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Jon Hunter" <jonathanh@...dia.com>,
	"Paul Walmsley" <paul@...an.com>,
	"Lokesh Vutla" <lokeshvutla@...com>,
	"Tero Kristo" <t-kristo@...com>
Subject: [PATCH 3.16 006/114] ARM: OMAP2+: hwmod: Fix updating of
 sysconfig register

3.16.36-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Lokesh Vutla <lokeshvutla@...com>

commit 3ca4a238106dedc285193ee47f494a6584b6fd2f upstream.

Commit 127500ccb766f ("ARM: OMAP2+: Only write the sysconfig on idle
when necessary") talks about verification of sysconfig cache value before
updating it, only during idle path. But the patch is adding the
verification in the enable path. So, adding the check in a proper place
as per the commit description.

Not keeping this check during enable path as there is a chance of losing
context and it is safe to do on idle as the context of the register will
never be lost while the device is active.

Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
Acked-by: Tero Kristo <t-kristo@...com>
Cc: Jon Hunter <jonathanh@...dia.com>
Fixes: commit 127500ccb766 "ARM: OMAP2+: Only write the sysconfig on idle when necessary"
[paul@...an.com: appears to have been caused by my own mismerge of the
 originally posted patch]
Signed-off-by: Paul Walmsley <paul@...an.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/arm/mach-omap2/omap_hwmod.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -1439,9 +1439,7 @@ static void _enable_sysc(struct omap_hwm
 	    (sf & SYSC_HAS_CLOCKACTIVITY))
 		_set_clockactivity(oh, oh->class->sysc->clockact, &v);
 
-	/* If the cached value is the same as the new value, skip the write */
-	if (oh->_sysc_cache != v)
-		_write_sysconfig(v, oh);
+	_write_sysconfig(v, oh);
 
 	/*
 	 * Set the autoidle bit only after setting the smartidle bit
@@ -1504,7 +1502,9 @@ static void _idle_sysc(struct omap_hwmod
 		_set_master_standbymode(oh, idlemode, &v);
 	}
 
-	_write_sysconfig(v, oh);
+	/* If the cached value is the same as the new value, skip the write */
+	if (oh->_sysc_cache != v)
+		_write_sysconfig(v, oh);
 }
 
 /**