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Commit efa3cb15 authored by Daniel Kurtz's avatar Daniel Kurtz Committed by Jean Delvare
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i2c-i801: Refactor use of LAST_BYTE in i801_block_transaction_byte_by_byte 



As a slight optimization, pull some logic out of the polling loop during
byte-by-byte transactions by just setting the I801_LAST_BYTE bit, as
defined in the i801 (PCH) datasheet, when reading the last byte of a
byte-by-byte I2C_SMBUS_READ.

Signed-off-by: default avatarDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent fda2f4af

drivers/i2c/busses/i2c-i801.c

+14 −14
Original line number Diff line number Diff line
@@ -117,8 +117,7 @@ 
#define I801_PROC_CALL		0x10	/* unimplemented */

#define I801_BLOCK_DATA		0x14

#define I801_I2C_BLOCK_DATA	0x18	/* ICH5 and later */

#define I801_BLOCK_LAST		0x34

#define I801_I2C_BLOCK_LAST	0x38	/* ICH5 and later */

#define I801_LAST_BYTE		0x20

#define I801_START		0x40

#define I801_PEC_EN		0x80	/* ICH3 and later */
@@ -338,6 +337,11 @@ static int i801_block_transaction_by_block(struct i801_priv *priv, 
	return 0;

}



/*

 * For "byte-by-byte" block transactions:

 *   I2C write uses cmd=I801_BLOCK_DATA, I2C_EN=1

 *   I2C read uses cmd=I801_I2C_BLOCK_DATA

 */

static int i801_block_transaction_byte_by_byte(struct i801_priv *priv,

					       union i2c_smbus_data *data,

					       char read_write, int command,
@@ -360,19 +364,15 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, 
		outb_p(data->block[1], SMBBLKDAT(priv));

	}



	for (i = 1; i <= len; i++) {

		if (i == len && read_write == I2C_SMBUS_READ) {

			if (command == I2C_SMBUS_I2C_BLOCK_DATA)

				smbcmd = I801_I2C_BLOCK_LAST;

			else

				smbcmd = I801_BLOCK_LAST;

		} else {

			if (command == I2C_SMBUS_I2C_BLOCK_DATA

			 && read_write == I2C_SMBUS_READ)

	if (command == I2C_SMBUS_I2C_BLOCK_DATA &&

	    read_write == I2C_SMBUS_READ)

		smbcmd = I801_I2C_BLOCK_DATA;

	else

		smbcmd = I801_BLOCK_DATA;

		}



	for (i = 1; i <= len; i++) {

		if (i == len && read_write == I2C_SMBUS_READ)

			smbcmd |= I801_LAST_BYTE;

		outb_p(smbcmd | ENABLE_INT9, SMBHSTCNT(priv));



		if (i == 1)