i2c-au1550: Fix a misused register problem
Fix a "mis-used register" problem on the AMD MIPS Alchemy au1550
I2C interface.
In summary, the programmable serial controller seems to hang the kernel
when I send a single 'address' byte on the I2C bus. The patch
essentially uses the PSC_SMBSTAT register's TE (transmit FIFO empty)
bit to check when the transmit FIFO is empty, instead of using the
PSC_SMBEVNT register's TU (transmit underflow) bit. Using the TE bit
fixed the hang problem.
Signed-off-by: Chris David <cd@chrisdavid.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
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 d7e7c35..2f68416 100644
--- a/drivers/i2c/busses/i2c-au1550.c
+++ b/drivers/i2c/busses/i2c-au1550.c
@@ -48,17 +48,14 @@
sp = (volatile psc_smb_t *)(adap->psc_base);
- /* Wait for Tx FIFO Underflow.
+ /* Wait for Tx Buffer Empty
*/
for (i = 0; i < adap->xfer_timeout; i++) {
- stat = sp->psc_smbevnt;
+ stat = sp->psc_smbstat;
au_sync();
- if ((stat & PSC_SMBEVNT_TU) != 0) {
- /* Clear it. */
- sp->psc_smbevnt = PSC_SMBEVNT_TU;
- au_sync();
+ if ((stat & PSC_SMBSTAT_TE) != 0)
return 0;
- }
+
udelay(1);
}