From: Heiner Kallweit <hkallweit1@gmail.com>
To: "Tod E. Kurt" <tod@todbot.com>
Cc: "open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
Linux USB Mailing List <linux-usb@vger.kernel.org>
Subject: Re: Linux "hid_led" vs "hidraw" USB HID question
Date: Sun, 10 Nov 2019 18:25:09 +0100 [thread overview]
Message-ID: <ab4e0840-72ee-4e65-db17-083c187b03ec@gmail.com> (raw)
In-Reply-To: <8A4D1E2D-9918-4A6C-9F8A-6447EE50F9F7@todbot.com>
On 10.11.2019 17:59, Tod E. Kurt wrote:
> Hi Heiner, (and others on the list)
>
> Thanks for your quick and detailed response.
>
> I am endeavoring to try the patch out now. But I've not built a desktop Linux kernel or kernel modules in about 15 years. Do you have a preferred recipe for applying this patch to an existing distro? Since 'hid-quirks' isn't a module, this means recompiling the entire HID driver, correct? I mostly test against various modern Ubuntu or Raspian flavors of Debian, if that matters.
>
See e.g. here: https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel
> Also, is there a mitigation for users running production distros that doesn't involve a recompile?
>
I don't think so (at least from kernel perspective). What you could do is adding an integration with
the /sys/class/led interface in your library (if it should be suitable for your use cases) and
auto-detect which interface to use.
> Thanks,
> -=Tod
>
Heiner
>> On Nov 10, 2019, at 2:44 a, Heiner Kallweit <hkallweit1@gmail.com> wrote:
>>
>> On 10.11.2019 04:26, Tod E. Kurt wrote:
>>> HiI
>>>
>> Hi Tod,
>>
>>> Since you are listed as author of "hid-led.c":
>>> https://github.com/torvalds/linux/blob/master/drivers/hid/hid-led.c,
>>> I was wondering if you could offer some insight on an issue I'm seeing.
>>> I'm a maintainer of "hidapi" and "node-hid", cross-platform C and NodeJs libraries for accessing HID devices, and I'm the creator of the ThingM blink(1) USB LED that "hid-led" controls.
>>>
>>> On the distros I've seen (Ubuntu, Raspian) where "hid-led" is enabled, when inserting a blink(1) device, the "hid-led" driver appears to grab the device and remove it from available "hidraw" devices. This makes generic hidraw-based systems (like "hidapi" and the upcoming Chrome WebHID) unable to see the blink(1)
>>>
>>> I have tried blacklisting the "hid-led" module but the problem persist. Ffrom dmesg and lsmod the module does appear to not be loaded on reboot.
>>>
>>> Any insights on what's going on? Any tips on how to debug this or how to prevent this from occurring?
>>>
>> When hid-led was written it was needed to add the LED devices to hid_have_special_driver list.
>> Else the driver can't take control over the device. Side effect is that even if hid-led
>> isn't loaded hid-generic can't take control.
>> I think since e04a0442d33b ("HID: core: remove the absolute need of hid_have_special_driver[]")
>> it's no longer needed to have the LED devices in hid_have_special_driver.
>> Could you please test the following patch? If hid-led is loaded is should control the
>> device, if it's blacklisted hid-generic should have the control.
>>
>>
>> diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
>> index c50bcd967..bdaab79f7 100644
>> --- a/drivers/hid/hid-quirks.c
>> +++ b/drivers/hid/hid-quirks.c
>> @@ -419,13 +419,6 @@ static const struct hid_device_id hid_have_special_driver[] = {
>> #if IS_ENABLED(CONFIG_HID_LCPOWER)
>> { HID_USB_DEVICE(USB_VENDOR_ID_LCPOWER, USB_DEVICE_ID_LCPOWER_LC1000) },
>> #endif
>> -#if IS_ENABLED(CONFIG_HID_LED)
>> - { HID_USB_DEVICE(USB_VENDOR_ID_DREAM_CHEEKY, USB_DEVICE_ID_DREAM_CHEEKY_WN) },
>> - { HID_USB_DEVICE(USB_VENDOR_ID_DREAM_CHEEKY, USB_DEVICE_ID_DREAM_CHEEKY_FA) },
>> - { HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_LUXAFOR) },
>> - { HID_USB_DEVICE(USB_VENDOR_ID_RISO_KAGAKU, USB_DEVICE_ID_RI_KA_WEBMAIL) },
>> - { HID_USB_DEVICE(USB_VENDOR_ID_THINGM, USB_DEVICE_ID_BLINK1) },
>> -#endif
>> #if IS_ENABLED(CONFIG_HID_LENOVO)
>> { HID_USB_DEVICE(USB_VENDOR_ID_LENOVO, USB_DEVICE_ID_LENOVO_TPKBD) },
>> { HID_USB_DEVICE(USB_VENDOR_ID_LENOVO, USB_DEVICE_ID_LENOVO_CUSBKBD) },
>> --
>> 2.24.0
>>
>>> I can send you blink(1) devices and "hidapi" test programs if you'd like to try to replicate this.
>>>
>> Thanks for the offer, I've got a blink(1) already. Just tested the patch with this device
>> and it worked properly like described above.
>>
>>> Thanks!
>>> -=Tod
>>
>> Heiner
>
>
next prev parent reply other threads:[~2019-11-10 17:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <6A37A3D7-96A6-49A4-83E5-ABE5DB417E8B@todbot.com>
2019-11-10 10:44 ` Linux "hid_led" vs "hidraw" USB HID question Heiner Kallweit
2019-11-10 16:59 ` Tod E. Kurt
2019-11-10 17:25 ` Heiner Kallweit [this message]
2019-11-10 23:07 ` Tod E. Kurt
2019-11-11 21:31 ` Heiner Kallweit
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