i2c-au1550: properly terminate zero-byte transfers
Zero-bytes transfers would leave the bus transaction unfinished
(no i2c stop is sent), with the following transfer actually
sending the slave address to the previously addressed device,
resulting in weird device failures (e.g. reset minute register
values in my RTC).
This patch instructs the controller to send an I2C STOP right after
the slave address in case of a zero-byte transfer.
Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/busses/i2c-au1550.c b/drivers/i2c/busses/i2c-au1550.c
index 2f68416..7d51a43 100644
--- a/drivers/i2c/busses/i2c-au1550.c
+++ b/drivers/i2c/busses/i2c-au1550.c
@@ -105,7 +105,7 @@
}
static int
-do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd)
+do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q)
{
volatile psc_smb_t *sp;
u32 stat;
@@ -134,6 +134,10 @@
if (rd)
addr |= 1;
+ /* zero-byte xfers stop immediately */
+ if (q)
+ addr |= PSC_SMBTXRX_STP;
+
/* Put byte into fifo, start up master.
*/
sp->psc_smbtxrx = addr;
@@ -142,7 +146,7 @@
au_sync();
if (wait_ack(adap))
return -EIO;
- return 0;
+ return (q) ? wait_master_done(adap) : 0;
}
static u32
@@ -262,7 +266,8 @@
for (i = 0; !err && i < num; i++) {
p = &msgs[i];
- err = do_address(adap, p->addr, p->flags & I2C_M_RD);
+ err = do_address(adap, p->addr, p->flags & I2C_M_RD,
+ (p->len == 0));
if (err || !p->len)
continue;
if (p->flags & I2C_M_RD)