Re: gma500: Other things that I could work on

[Patrik Jakobsson <patrik.r.jakobsson@gmail.com>]

On Wed, Apr 3, 2013 at 5:21 PM, Kero <kero@chello.nl> wrote:
> Hi,
>
> I would not mind improving use of my Asus EeePC X101CH with Cedar View / gma3600
> a bit more. But a barrier is knowledge of the hardware. Meddling with existing (initialization)
> code is possible, but for point 1 and 3 below that is not going to cut, it, I expect.

It would be very useful if you could help out with cedarview. Even if it's just
by testing patches. A big problem for me is that I don't have the hardware so
it's easy to break things without even knowing about it.

>
> Does anyone have pointers? Who should I talk to about specifications?
> I know Intel is not forthcoming with documentation, yet several people have
> made contributions for poulsbo and later versions of the hardware.
> How did you get the required knowledge?

Most of the mode setting stuff are variations of Intel hardware. You can find
specifications at https://01.org/linuxgraphics/ and it's also useful to look at
the Intel i915 drm driver for reference. It is quite a mix so you need to look
at bits and pieces from several of the Intel generations and try to match them
together.

For the non-Intel parts there are some drivers that never made it into mainline
but is still available online. Some parts are open and some are closed.

There is also a fair amount of guessing and probing needed.

>
> Things I might, in order of personal preference, in due time (after holiday), take a look at:
> 1) would be nice to have the full 1024x600 on the external VGA and HDMI
>    I had a chance to try another monitor over HDMI, same result: only 800x600 visible.
> 2) booting with either VGA or HDMI plugged in, yields two black screens: both the laptop
>    and the monitor. Un- + re-plugging has no visible effect.
> 3) the Fn keys for the backlight induce a response in the backlight, but only with
>    tiny results; /sys/class/backlight/psb-bl/brightness works fine, though
> 4) when using modules, initialization from hibernation is not good enough:
>    my screen stays black; without using modules, the kernel boots normally, and everything is fine.
> 5) initialization from suspend is not good enough: my Asus stays in
>    some text mode (80x25?), but shows garbage (possibly data from the desired console or
>    graphics mode, since sometimes there are reactions correlated to actions)
>    Switching tty or using `chvt` do not improve anything.
>    NB: hibernating and booting solves this.

There are quite a few issues that needs to be addressed and code that needs to
be refactored. I suggest you just dig in and get your hands dirty.

-Patrik