linux-kernel - [PATCH 4/8 v3] i2c: i801: check and return errors during byte-by-byte transfers

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Date:	Wed, 27 Jun 2012 21:54:11 +0800
From:	Daniel Kurtz <djkurtz@...omium.org>
To:	Jean Delvare <khali@...ux-fr.org>, Ben Dooks <ben-linux@...ff.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Seth Heasley <seth.heasley@...el.com>
Cc:	Olof Johansson <olof@...om.net>,
	Benson Leung <bleung@...omium.org>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, Daniel Kurtz <djkurtz@...omium.org>
Subject: [PATCH 4/8 v3] i2c: i801: check and return errors during byte-by-byte transfers

If an error is detected in the polling loop, abort the transaction and
return an error code.

 * DEV_ERR is set if the device does not respond with an acknowledge, and
the SMBus controller times out (minimum 25ms).
 * BUS_ERR is set if a bus arbitration collision is detected.  In other
words, when the SMBus controller tries to generate a START condition, but
detects that the SMBDATA is being held low, usually by another SMBus/I2C
master.
 * FAILED is only set if a the transaction is set by software (using the
SMBHSTCNT KILL bit).

Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>
---
 drivers/i2c/busses/i2c-i801.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 6a53338..ba56b74 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -131,9 +131,11 @@
 #define SMBHSTSTS_INTR		0x02
 #define SMBHSTSTS_HOST_BUSY	0x01
 
-#define STATUS_FLAGS		(SMBHSTSTS_BYTE_DONE | SMBHSTSTS_FAILED | \
-				 SMBHSTSTS_BUS_ERR | SMBHSTSTS_DEV_ERR | \
-				 SMBHSTSTS_INTR)
+#define STATUS_ERROR_FLAGS	(SMBHSTSTS_FAILED | SMBHSTSTS_BUS_ERR | \
+				 SMBHSTSTS_DEV_ERR)
+
+#define STATUS_FLAGS		(SMBHSTSTS_BYTE_DONE | SMBHSTSTS_INTR | \
+				 STATUS_ERROR_FLAGS)
 
 /* Older devices have their ID defined in <linux/pci_ids.h> */
 #define PCI_DEVICE_ID_INTEL_COUGARPOINT_SMBUS	0x1c22
@@ -385,7 +387,7 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv,
 		do {
 			usleep_range(250, 500);
 			status = inb_p(SMBHSTSTS(priv));
-		} while ((!(status & SMBHSTSTS_BYTE_DONE))
+		} while (!(status & (SMBHSTSTS_BYTE_DONE | STATUS_ERROR_FLAGS))
 			 && (timeout++ < MAX_RETRIES));
 
 		result = i801_check_post(priv, status, timeout > MAX_RETRIES);
-- 
1.7.7.3

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