HID: ft260: fix device removal due to USB disconnect

This commit fixes a functional regression introduced by the commit 82f09a637dd3
("HID: ft260: improve error handling of ft260_hid_feature_report_get()")
when upon USB disconnect, the FTDI FT260 i2c device is still available within
the /dev folder.

In my company's product, where the host USB to FT260 USB connection is
hard-wired in the PCB, the issue is not reproducible. To reproduce it, I used
the VirtualBox Ubuntu 20.04 VM and the UMFT260EV1A development module for the
FTDI FT260 chip:

Plug the UMFT260EV1A module into a USB port and attach it to VM.

The VM shows 2 i2c devices under the /dev:
    michael@michael-VirtualBox:~$ ls /dev/i2c-*
    /dev/i2c-0  /dev/i2c-1

The i2c-0 is not related to the FTDI FT260:
    michael@michael-VirtualBox:~$ cat /sys/bus/i2c/devices/i2c-0/name
    SMBus PIIX4 adapter at 4100

The i2c-1 is created by hid-ft260.ko:
    michael@michael-VirtualBox:~$ cat /sys/bus/i2c/devices/i2c-1/name
    FT260 usb-i2c bridge on hidraw1

Now, detach the FTDI FT260 USB device from VM. We expect the /dev/i2c-1
to disappear, but it's still here:
    michael@michael-VirtualBox:~$ ls /dev/i2c-*
    /dev/i2c-0  /dev/i2c-1

And the kernel log shows:
    [  +0.001202] usb 2-2: USB disconnect, device number 3
    [  +0.000109] ft260 0003:0403:6030.0002: failed to retrieve system status
    [  +0.000316] ft260 0003:0403:6030.0003: failed to retrieve system status

It happens because the commit 82f09a637dd3 changed the ft260_get_system_config()
return logic. This caused the ft260_is_interface_enabled() to exit with error
upon the FT260 device USB disconnect, which in turn, aborted the ft260_remove()
before deleting the FT260 i2c device and cleaning its sysfs stuff.

This commit restores the FT260 USB removal functionality and improves the
ft260_is_interface_enabled() code to handle correctly all chip modes defined
by the device interface configuration pins DCNF0 and DCNF1.

Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
Acked-by: Aaron Jones (FTDI-UK) <aaron.jones@ftdichip.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 6f10df2042c44b659cbe6d00bcd5079416a3007e..4ef1c3b8094ea036ce382232c255e00d7d849be2 100644 (file)
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c
@@ -742,7 +742,7 @@ static int ft260_is_interface_enabled(struct hid_device *hdev)
        int ret;
 
        ret = ft260_get_system_config(hdev, &cfg);
-       if (ret)
+       if (ret < 0)
                return ret;
 
        ft260_dbg("interface:  0x%02x\n", interface);
@@ -754,23 +754,16 @@ static int ft260_is_interface_enabled(struct hid_device *hdev)
        switch (cfg.chip_mode) {
        case FT260_MODE_ALL:
        case FT260_MODE_BOTH:
-               if (interface == 1) {
+               if (interface == 1)
                        hid_info(hdev, "uart interface is not supported\n");
-                       return 0;
-               }
-               ret = 1;
+               else
+                       ret = 1;
                break;
        case FT260_MODE_UART:
-               if (interface == 0) {
-                       hid_info(hdev, "uart is unsupported on interface 0\n");
-                       ret = 0;
-               }
+               hid_info(hdev, "uart interface is not supported\n");
                break;
        case FT260_MODE_I2C:
-               if (interface == 1) {
-                       hid_info(hdev, "i2c is unsupported on interface 1\n");
-                       ret = 0;
-               }
+               ret = 1;
                break;
        }
        return ret;
@@ -1004,11 +997,9 @@ err_hid_stop:
 
 static void ft260_remove(struct hid_device *hdev)
 {
-       int ret;
        struct ft260_device *dev = hid_get_drvdata(hdev);
 
-       ret = ft260_is_interface_enabled(hdev);
-       if (ret <= 0)
+       if (!dev)
                return;
 
        sysfs_remove_group(&hdev->dev.kobj, &ft260_attr_group);