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HID: ft260: ft260_xfer_status routine cleanup

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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>
This commit is contained in:
Michael Zaidman 2022-11-05 23:11:39 +02:00 committed by Jiri Kosina
parent 334fe5d3a9
commit f45d50ede6
1 changed files with 10 additions and 20 deletions
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30
drivers/hid/hid-ft260.c
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@ -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);