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From: Jiri Kosina <>
To: Michael Zaidman <>
Subject: Re: [PATCH v2] HID: ft260: fix device removal due to USB disconnect
Date: Thu, 29 Jul 2021 12:39:03 +0200 (CEST)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, 29 Jul 2021, Michael Zaidman wrote:

> 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 <>
> Acked-by: Aaron Jones (FTDI-UK) <>

Thanks for the respin. Queued in for-5.14/upstream-fixes.

Jiri Kosina

      reply	other threads:[~2021-07-29 10:39 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-20 14:49 [PATCH v1] " Michael Zaidman
2021-07-28  9:47 ` Jiri Kosina
2021-07-29 10:26   ` [PATCH v2] " Michael Zaidman
2021-07-29 10:39     ` Jiri Kosina [this message]

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