Re: [PATCH] toshiba_acpi: Fix keyboard backight sysfs entries not being updated

From: Azael Avalos
Date: Fri Nov 20 2015 - 18:55:15 EST

Hi Darren,

2015-11-20 16:39 GMT-07:00 Darren Hart <dvhart@xxxxxxxxxxxxx>:
> On Mon, Nov 16, 2015 at 12:59:31PM -0700, Azael Avalos wrote:
>> Certain Toshiba models with the second generation keyboard backlight
>> (type 2) do not generate the keyboard backlight changed event (0x92),
>> and thus, the sysfs entries are never being updated.
>> This patch adds a workquee and a global boolean variable to address
>> the issue.
>> For those models that do generate the event, the sysfs entries are
>> being updated via the *notify function and the boolean is set to
>> true to avoid a second call to update the entries.
>> For those models that do not generate the event, the workquee is
>> used to update the sysfs entries and also to emulate the event via
>> netlink, to make userspace aware of such change.
> Thanks Azael,
> Rather than ask you to wait while I research workqueues and their use more, what
> is it about this task that requires a workqueue? Why can we not call what's in
> the workqueue below directly from the kbd_backlight_mode_store sysfs write
> callback?

I used the workquee to let the sysfs *store function to finish w/o affecting
the "refresh" of the sysfs entries.

Previously the sysfs_update_group resided inside the *store function,
but caused a lock everytime the keyboard mode was changed, and the
sysfs entries were never updated, this was fixed by moving such function
to the *notify function, but turns out that some models do not fire such


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