linux-kernel - [PATCH 3.8 13/81] i2c: omap: Clear ARDY bit twice

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Message-Id: <1383069882-11437-14-git-send-email-kamal@canonical.com>
Date:	Tue, 29 Oct 2013 11:03:34 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Grygorii Strashko <grygorii.strashko@...com>,
	Taras Kondratiuk <taras.kondratiuk@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.8 13/81] i2c: omap: Clear ARDY bit twice

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

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

From: Taras Kondratiuk <taras.kondratiuk@...aro.org>

commit 4cdbf7d346e7461c3b93a26707c852e2c9db3753 upstream.

Initially commit cb527ede1bf6ff2008a025606f25344b8ed7b4ac
"i2c-omap: Double clear of ARDY status in IRQ handler"
added a workaround for undocumented errata ProDB0017052.
But then commit 1d7afc95946487945cc7f5019b41255b72224b70
"i2c: omap: ack IRQ in parts" refactored code and missed
one of ARDY clearings. So current code violates errata.
It causes often i2c bus timeouts on my Pandaboard.

This patch adds a second clearing in place.

Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@...aro.org>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/i2c/busses/i2c-omap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 4cc2f05..6fc54cd 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -941,6 +941,9 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
 		/*
 		 * ProDB0017052: Clear ARDY bit twice
 		 */
+		if (stat & OMAP_I2C_STAT_ARDY)
+			omap_i2c_ack_stat(dev, OMAP_I2C_STAT_ARDY);
+
 		if (stat & (OMAP_I2C_STAT_ARDY | OMAP_I2C_STAT_NACK |
 					OMAP_I2C_STAT_AL)) {
 			omap_i2c_ack_stat(dev, (OMAP_I2C_STAT_RRDY |
-- 
1.8.1.2

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