linux-kernel - [PATCH 6/7] ARM: OMAP: Disable POSTED mode for errata i103 and i767

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Message-ID: <1385415876-12387-7-git-send-email-joelf@ti.com>
Date:	Mon, 25 Nov 2013 15:44:35 -0600
From:	Joel Fernandes <joelf@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	<linux-omap@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Joel Fernandes <joelf@...com>,
	Santosh Shilimkar <santosh.shilimkar@...com>
Subject: [PATCH 6/7] ARM: OMAP: Disable POSTED mode for errata i103 and i767

Enabling of Posted mode is seen to cause problems on dmtimer modules on AM33xx
(much like other OMAPs).  Reference discussions on forums [1] [2]. Earlier
patch solving this on other OMAPs [3].

For OMAP SoCs with this errata, the fix has been to not enable Posted mode.
However, on some SoCs (atleast AM33xx) which carry this errata, Posted mode
is enabled on reset. So we not only need to ignore enabling of the POSTED bit
when the timer is requested, but also disable Posted mode if errata is present.

[1] http://e2e.ti.com/support/arm/sitara_arm/f/791/t/285744.aspx
[2] http://e2e.ti.com/support/arm/sitara_arm/f/791/t/270632.aspx
[3] http://www.spinics.net/lists/linux-omap/msg81770.html

Reported-by: Russ Dill <russ.dill@...com>
Cc: Santosh Shilimkar <santosh.shilimkar@...com>
Signed-off-by: Joel Fernandes <joelf@...com>
---
 arch/arm/plat-omap/include/plat/dmtimer.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/plat-omap/include/plat/dmtimer.h b/arch/arm/plat-omap/include/plat/dmtimer.h
index fb92abb..2861b15 100644
--- a/arch/arm/plat-omap/include/plat/dmtimer.h
+++ b/arch/arm/plat-omap/include/plat/dmtimer.h
@@ -336,8 +336,11 @@ static inline void __omap_dm_timer_enable_posted(struct omap_dm_timer *timer)
 	if (timer->posted)
 		return;
 
-	if (timer->errata & OMAP_TIMER_ERRATA_I103_I767)
+	if (timer->errata & OMAP_TIMER_ERRATA_I103_I767) {
+		timer->posted = OMAP_TIMER_NONPOSTED;
+		__omap_dm_timer_write(timer, OMAP_TIMER_IF_CTRL_REG, 0, 0);
 		return;
+	}
 
 	__omap_dm_timer_write(timer, OMAP_TIMER_IF_CTRL_REG,
 			      OMAP_TIMER_CTRL_POSTED, 0);
-- 
1.8.1.2

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