Commit f45d50ed authored by Michael Zaidman's avatar Michael Zaidman Committed by Jiri Kosina
Browse files

HID: ft260: ft260_xfer_status routine cleanup 



After clarifying with FTDI's support, it turned out that the error
condition (bit 1) in byte 1 of the i2c status HID report is a status
bit reflecting all error conditions. When bits 2, 3, or 4 are raised
to 1, bit 1 is set to 1 also. Since the ft260_xfer_status routine tests
the error condition bit and exits in the case of an error, the program
flow never reaches the conditional expressions for 2, 3, and 4 bits when
any of them indicates an error state. Though these expressions are never
evaluated to true, they are checked several times per IO, increasing the
ft260_xfer_status polling cycle duration.

The patch removes the conditional expressions for 2, 3, and 4 bits in
byte 1 of the i2c status HID report.

Signed-off-by: default avatarMichael Zaidman <michael.zaidman@gmail.com>
Tested-by: default avatarGuillaume Champagne <champagne.guillaume.c@gmail.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 334fe5d3

drivers/hid/hid-ft260.c

+10 −20
Original line number Diff line number Diff line
@@ -313,27 +313,17 @@ static int ft260_xfer_status(struct ft260_device *dev) 
	if (report.bus_status & FT260_I2C_STATUS_CTRL_BUSY)

		return -EAGAIN;



	if (report.bus_status & FT260_I2C_STATUS_BUS_BUSY)

		return -EBUSY;



	if (report.bus_status & FT260_I2C_STATUS_ERROR)

	/*

	 * The error condition (bit 1) is a status bit reflecting any

	 * error conditions. When any of the bits 2, 3, or 4 are raised

	 * to 1, bit 1 is also set to 1.

	 */

	if (report.bus_status & FT260_I2C_STATUS_ERROR) {

		hid_err(hdev, "i2c bus error: %#02x\n", report.bus_status);

		return -EIO;

	}



	ret = -EIO;



	if (report.bus_status & FT260_I2C_STATUS_ADDR_NO_ACK)

		ft260_dbg("unacknowledged address\n");



	if (report.bus_status & FT260_I2C_STATUS_DATA_NO_ACK)

		ft260_dbg("unacknowledged data\n");



	if (report.bus_status & FT260_I2C_STATUS_ARBITR_LOST)

		ft260_dbg("arbitration loss\n");



	if (report.bus_status & FT260_I2C_STATUS_CTRL_IDLE)

		ret = 0;



	return ret;

	return 0;

}



static int ft260_hid_output_report(struct hid_device *hdev, u8 *data,
@@ -376,7 +366,7 @@ static int ft260_hid_output_report_check_status(struct ft260_device *dev, 
			break;

	} while (--try);



	if (ret == 0 || ret == -EBUSY)

	if (ret == 0)

		return 0;



	ft260_i2c_reset(hdev);