i2c: i801: Handle SMBAUXCTL_E32B in i801_block_transaction_by_block only

Currently we touch SMBAUXCTL even if not needed. That's the case for block
commands that don't use block buffer mode, either because block buffer
mode isn't available or because it's not supported for the respective
command (e.g. I2C block transfer). Improve this by setting/resetting
SMBAUXCTL_E32B in i801_block_transaction_by_block() only.

Small downside is that we now access SMBAUXCTL twice for transactions
that use PEC and block buffer mode. But this should a rather rare case
and the impact is negligible.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-i801.c

@@ -511,19 +511,23 @@ static int i801_block_transaction_by_block(struct i801_priv *priv,
 
 	status = i801_transaction(priv, xact);
 	if (status)
-		return status;
+		goto out;
 
 	if (read_write == I2C_SMBUS_READ ||
 	    command == I2C_SMBUS_BLOCK_PROC_CALL) {
 		len = inb_p(SMBHSTDAT0(priv));
-		if (len < 1 || len > I2C_SMBUS_BLOCK_MAX)
-			return -EPROTO;
+		if (len < 1 || len > I2C_SMBUS_BLOCK_MAX) {
+			status = -EPROTO;
+			goto out;
+		}
 
 		data->block[0] = len;
 		for (i = 0; i < len; i++)
 			data->block[i + 1] = inb_p(SMBBLKDAT(priv));
 	}
-	return 0;
+out:
+	outb_p(inb_p(SMBAUXCTL(priv)) & ~SMBAUXCTL_E32B, SMBAUXCTL(priv));
+	return status;
 }
 
 static void i801_isr_byte_done(struct i801_priv *priv)
@@ -921,11 +925,10 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
 		ret = i801_simple_transaction(priv, data, read_write, size);
 
 	/* Some BIOSes don't like it when PEC is enabled at reboot or resume
-	   time, so we forcibly disable it after every transaction. Turn off
-	   E32B for the same reason. */
-	if (hwpec || block)
-		outb_p(inb_p(SMBAUXCTL(priv)) &
-		       ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv));
+	 * time, so we forcibly disable it after every transaction.
+	 */
+	if (hwpec)
+		outb_p(inb_p(SMBAUXCTL(priv)) & ~SMBAUXCTL_CRC, SMBAUXCTL(priv));
 out:
 	/*
 	 * Unlock the SMBus device for use by BIOS/ACPI,