Re: is it possible to temporarily not let user mode get hid input event

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Hi

On Sun, Feb 23, 2014 at 7:52 AM, loody <miloody@xxxxxxxxx> wrote:
> hi David:
>
> Thanks for your suggestion.
> 2014-02-23 0:56 GMT+08:00 David Herrmann <dh.herrmann@xxxxxxxxx>:
>> Hi
>>
>> On Sat, Feb 22, 2014 at 5:35 PM, loody <miloody@xxxxxxxxx> wrote:
>>> hi all:
>>> is there any kernel hid module parameter or test program can
>>> temporarily not letting user mode program not receiving hid event?
>>> 1. My hid kos are still inserted in.
>>> 2. the kernel usb driver is working well; that mean kernel usb driver
>>> still handle interrupt transaction.
>>>
>>> I just not want user mode program see the hid event for a while,
>>
>> For each connected HID device, there is a driver bound to it that
>> reads the events and forwards them to HID core. What you can do, is to
>> unbind a driver on a given device:
>>   echo "<your-device-name>" >/sys/bus/hid/drivers/<driver-name>/unbind
>> The device-name is the directory name in:
>>   /sys/bus/hid/devices/
>> The driver name is usually "hid-generic" but can be figured out for
>> each device by looking at the "driver" symlink in it's directry.
>> However, this is *really* just meant for debugging. This is not
>> recommended for anything serious. There is no support for that and if
>> you don't know what all this does, you shouldn't use it.
>>
>> There is no proper way to disable a single device in the kernel.
>> User-space is supposed to control device-access so we probably won't
>> add such features to the kernel. If you describe your use-case in more
>> details, we can try to give hints how to get that working.
>
> Sorry for not describing our situation clearer previously,
>
> The problem we met like below
> a. once plug in usb hid mouse and fast moving mouse
> b. the screen will get blur.
>
> We want to know whether the screen blur is caused by
> 1. the interrupt frequency of usb mouse is too high for our embedded
> system that make video decode slow
> 2. something wrong between hw cursor and video overlay.
>
> if we can deceive user mode program there is no mouse event, but
> kernel usb level still get hid interrupt transaction.
> We may clarify whether above 1) conclusion is correct.
>
> Appreciate your kind help :-)

You can unload the HID driver as described above, but that's unlikely
to fix any interrupt issues. How about you compile your kernel without
usbhid support? (CONFIG_USB_HID)

David
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