linux-kernel - Re: usbhid driver: replacing resume or using a post resume function

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Message-ID: <fd35fcc83b1a4ae5dd4daba3cf596c5d.squirrel@intranet.cs.nmsu.edu>
Date:	Wed, 27 Jan 2010 07:57:48 -0700
From:	"Rick L. Vinyard, Jr." <rvinyard@...nmsu.edu>
To:	"Jiri Kosina" <jkosina@...e.cz>
Cc:	"Linux" <linux-kernel@...r.kernel.org>,
	"Linux USB" <linux-usb@...r.kernel.org>
Subject: Re: usbhid driver: replacing resume or using a post resume function

Jiri Kosina wrote:
> On Tue, 26 Jan 2010, Rick L. Vinyard, Jr. wrote:
>
>> I was looking for an example of a hid driver that needs to customize
>> resume or provides a post resume function, but couldn't find one.
>>
>> I would like to implement some post resume code. In particular, the g13
>> on
>> resume loses the backlight color, LCD image and LED state. On resume, it
>> needs feature reports sent to re-establish these settings.
>>
>> However, I couldn't find a way to either provide a post resume function
>> or
>> replace resume with a call to hid_resume() followed by the feature
>> reports.
>>
>> Any suggestions?
>
> Current HID / USBHID code doesn't allow for that. But implementing that
> should be pretty straightforward, you can define callbacks in the
> hid_device struct and then redirect to them instead of the default ones,
> when they are initialized.

Sounds good. I was actually thinking of doing a post_reset() and
post_resume().

I think the most common case would be for something like the G13 to
re-establish settings, which from the few devices I'm familiar with would
need to restart the hid subsystem first and then re-establish through
feature reports, et. al. after the hid_resume().

Also, that means that usbhid's hid_resume() doesn't need to be exposed in
the API, or even need to be usb specific.

>
> If you submit this patch together (but separately) with your Logitech G13
> driver, there shouldn't be any obstacle merging it.
>

Sounds good.

Thanks,

Rick

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