Re: USB keyboard backlight powering down.
From: Gerry Reno
Date: Wed Oct 17 2012 - 10:10:03 EST
On 10/17/2012 08:55 AM, Josh Boyer wrote:
> On Tue, Oct 16, 2012 at 10:35:24AM -0700, Sarah Sharp wrote:
>> On Tue, Oct 16, 2012 at 09:54:36AM -0700, Greg Kroah-Hartman wrote:
>>> On Tue, Oct 16, 2012 at 12:45:56PM -0400, Michael Spang wrote:
>>>> On Tue, Oct 16, 2012 at 11:20 AM, Dave Jones <davej@xxxxxxxxxx> wrote:
>>>>> Gerry (CC'd) reported a bug to us that since 3.6.1, his illuminated
>>>>> Logitech USB keyboard doesn't light up until he hits a key, and then
>>>>> it immediately powers back off, defeating the purpose of having an
>>>>> illumated keyboard.
>>>>> Looking over the 3.6.1 changelog, I see this change, which sounds
>>>>> like it might be responsible ?
>>>>> commit ee537508bdc0c00b96ac497f3d82a68f820e6182
>>>>> Author: Michael Spang <spang@xxxxxxxxxxxx>
>>>>> Date: Fri Sep 14 13:05:49 2012 -0400
>>>>> Increase XHCI suspend timeout to 16ms
>>>> I don't think this is related to your problem, as this patch is in
>>>> suspend/resume code. It just allows the controller more time to halt.
>>> Yeah, that looks odd.
>>> But, (adding linux-usb@vger), I think we enabled some "put the device to
>>> sleep if it is idle" logic for all devices, which is what is looking
>>> like is happening here. The keyboard is being told to go to sleep in
>>> order to save power.
>>> We are saving more power, but it looks like the user wants to disable
>>> it, which makes sense for this device.
>>> So, do we do this from within the kernel with a blacklist, or rely on
>>> the user knowing how to poke the proper sysfs file to turn the keyboard
>>> back on?
>> This was the udev bug I was referring to, which I think is causing the
>> keyboard to have auto-suspend enabled:
>> udev shouldn't be enabling auto-suspend of USB hids by default, since
>> many of them don't send a wakeup to come out of suspend when they
>> should. For example, most USB mice only send a wakeup even when they
>> are clicked, not when they are moved. That causes the user to sit
>> there, frustrated, as they move their mouse and wonder why their screen
>> doesn't unblank. Other keyboards also lose keystrokes, which means if
>> you pause to compose your thoughts, the first couple letters you type
>> gets dropped.
> I know we fixed that bug for F17, F18, and rawhide. I did it myself.
> I don't think this is udev related, but we'll double check the version.
> Gerry, are you using udev-182-3.fc17 or newer on your F17 install?
There is an update available to 182-3 but I haven't installed it. Didn't know what it might impact.
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