Commit a202707e authored Oct 13, 2007 by Chris David Committed by Jean Delvare Oct 13, 2007

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>

parent 6662cbb9

drivers/i2c/busses/i2c-au1550.c

+4 −7

Original line number	Diff line number	Diff line
		@@ -48,17 +48,14 @@ wait_xfer_done(struct i2c_au1550_data *adap)

		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;
		au_sync();
		if ((stat & PSC_SMBEVNT_TU) != 0) {
		/* Clear it. */
		sp->psc_smbevnt = PSC_SMBEVNT_TU;
		stat = sp->psc_smbstat;
		au_sync();
		if ((stat & PSC_SMBSTAT_TE) != 0)
		return 0;
		}

		udelay(1);
		}