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List:       linux-i2c
Subject:    [PATCH 1/3] i2c-omap: Fix I2C status ACK
From:       Moiz Sonasath <m-sonasath () ti ! com>
Date:       2009-08-20 16:21:14
Message-ID: 1250785276-31713-2-git-send-email-m-sonasath () ti ! com
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From: Nishanth Menon <nm@ti.com>

I2C status ack for [RX]RDR and [RX]RDY could
cause race conditions of clearing the event
twice and a violation of the programing
sequence as defined in TRM This patch fixes
the same.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
---
 drivers/i2c/busses/i2c-omap.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index d258b02..94639d0 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -674,7 +674,14 @@ omap_i2c_isr(int this_irq, void *dev_id)
 
 		err = 0;
 complete:
-		omap_i2c_write_reg(dev, OMAP_I2C_STAT_REG, stat);
+		/*
+		 * Ack the stat in one go, but [R/X]DR and [R/X]RDY should be
+		 * acked after the data operation is complete.
+		 * Ref: TRM SWPU114Q Figure 18-31
+		 */
+		omap_i2c_write_reg(dev, OMAP_I2C_STAT_REG, stat &
+				~(OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR |
+				OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR));
 
 		if (stat & OMAP_I2C_STAT_NACK) {
 			err |= OMAP_I2C_STAT_NACK;
-- 
1.5.6.3

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