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: Michael Zaidman <michael.zaidman@gmail.com>
Tested-by: Guillaume Champagne <champagne.guillaume.c@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 79505c64dbfe72ebb00c518fde12ec0337d0d39c..a35201d68b15e4e73d8a5023bcece0cd5c144659 100644 (file)
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c
@@ -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);