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[PATCH 1/2] i2c-au1550: send i2c stop on error #2

To: i2c@lm-sensors.org
Subject: [PATCH 1/2] i2c-au1550: send i2c stop on error #2
From: Manuel Lauss <mano@roarinelk.homelinux.net>
Date: Wed, 16 May 2007 07:31:13 +0200
Cc: linux-mips@linux-mips.org, khali@linux-fr.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.11
When the au1550 i2c driver encounteres an error while addressing a slave
or has no data to send to a slave in the last i2c message, it returns to
the upper layers without issuing a i2c stop condition.  This for example
resulted in the minute register of the RTC on my board to be overwritten
with a random value on a following transfer.

Fix the driver to send a stop over the i2c bus if one of the following
2 conditions are met:
* error when addressing a slave
* no data to send in the last i2c message

Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>

--- a/drivers/i2c/busses/i2c-au1550.c   2007-04-26 05:08:32.000000000 +0200
+++ b/drivers/i2c/busses/i2c-au1550.c   2007-05-15 20:19:56.000000000 +0200
@@ -260,13 +260,20 @@ static int
 au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
 {
        struct i2c_au1550_data *adap = i2c_adap->algo_data;
+       volatile psc_smb_t *sp = (volatile psc_smb_t *)(adap->psc_base);
        struct i2c_msg *p;
        int i, err = 0;
 
        for (i = 0; !err && i < num; i++) {
                p = &msgs[i];
                err = do_address(adap, p->addr, p->flags & I2C_M_RD);
-               if (err || !p->len)
+               if (err || ((!p->len) && (i == (num - 1)))) {
+                       sp->psc_smbtxrx = PSC_SMBTXRX_STP;
+                       au_sync();
+                       wait_master_done(adap);
+                       continue;
+               }
+               if (!p->len)
                        continue;
                if (p->flags & I2C_M_RD)
                        err = i2c_read(adap, p->buf, p->len);

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