Message-ID: <71cd59b00909081439x56e6f789hbb92a3f058198a9e@mail.gmail.com>
Date:	Tue, 8 Sep 2009 23:39:35 +0200
From:	Corentin Chary <corentin.chary@...il.com>
To:	Greg KH <greg@...ah.com>
Cc:	Jakub Schmidtke <sjakub@...il.com>,
	acpi4asus-user@...ts.sourceforge.net,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Cleaning asus_oled

On Thu, Aug 6, 2009 at 10:01 PM, Greg KH<greg@...ah.com> wrote:
> On Wed, Aug 05, 2009 at 09:54:47AM +0200, Corentin Chary wrote:
>> On Tue, Aug 4, 2009 at 10:35 PM, Greg KH<greg@...ah.com> wrote:
>> > On Tue, Aug 04, 2009 at 08:40:10PM +0200, Corentin Chary wrote:
>> >> Hi,
>> >> I'm trying to clean the asus_oled driver, here is my git tree with
>> >> some trivial patchs.
>> >> http://git.iksaif.net/?p=acpi4asus.git;a=shortlog;h=refs/heads/asus_oled
>> >
>> > That's great!  But note, I need patches in email form, so you are going
>> > to use git format-patch to dig them out for me, right?  :)
>>
>> Yes, of course.
>>
>> >> Before working deeper, I wanted to discuss about the userspace interface:
>> >>
>> >> > TODO:
>> >> > [...]
>> >> >        - audit the userspace interface
>> >> >                - sysfs vs. char?
>> >>
>> >> First, should we move asus_oled functionalities in asus-laptop ?
>> >> Then the interface would be in sysfs under
>> >> /sys/devices/platform/asus-laptop/{picture|enable} ?
>> >
>> > Is that the way that other drivers of this kind of functionality work
>> > today?  If so, yes, that would be good.
>>
>> Hum, actually I think it is not a good idea. It is just an USB device, and
>> Asus may wan't to use it on motherboard on day. We should keep it
>> a simple usb driver.
>>
>> >> Else we can use /dev/asus_oled, with an ioctl (or a zero-size image)
>> >> to switch the OLED off.
>> >> But I don't think /sys/class/oled is a good place to be, because
>> >> /sys/class is for generic things.
>> >
>> > Like /sys/class/video_output?  There's got to be some other generic
>> > backlight driver class already, oh, hey, look at /sys/class/backlight!
>> >
>> > So, why not just use the backlight interface instead, that way you don't
>> > have to write custom userspace code for this specific platform?
>>
>> backlight interface is only to change screen brightness, so we can't
>> use that for an oled screen. There is an lcd class too, but it is used
>> for contrast.
>>
>> After some grepping in the kernel, it seems that there is no generic
>> lcd interface.
>> For example :
>> - drivers/parisc/led.c use a /proc/pdc/lcd file
>> - drivers/ans-lcd.c  use a /dev/anslcd file
>>
>> If you look at http://ssl.bulix.org/projects/lcd4linux/browser/trunk
>>
>> You'll see a lot of drv_***.c files, and each of them are for a
>> different kernel interface
>> (although some of them might don't use any interface).
>>
>> It seems that http://lcd-linux.sourceforge.net/ try to implement a
>> generic interface,
>> but only for alphanumeric displays, and it is not in mainline.
>
> But we could add it, right?  Care to ask those developers if we can do
> that?
>
>> This also could be a classic frambuffer device, but I don't think it's
>> the best way to go for this type of device.
>>
>> Time to write a generic oled/lcd pannel class ?
>
> Probably :)
>
> have fun,
>
> greg k-h
>

Hi,
I've seen your thread about the staging tree status.
I'm currently trying to get the hardware to work on asus_oled.
If I can get it, I'll maintain this driver as a part of the acpi4asus project.
Else, we will need to find another maintainer =).

Thanks,

-- 
Corentin Chary
http://xf.iksaif.net
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