[U-Boot] L2 cache and LCD on sunxi

[Hans de Goede]

Hi,

On 23-12-14 05:36, Simon Glass wrote:
> Hi Hans,
>
> On 22 December 2014 at 09:45, Hans de Goede <hdegoede at redhat.com> wrote:
>> Hi,
>>
>> On 21-12-14 19:52, Simon Glass wrote:
>>>
>>> Hi,
>>>
>>> I ran up a banana PI and noticed that HDMI works in U-Boot. Great!
>>>
>>> Scrolling seems very slow though - is the L2 cache disabled perhaps?
>>
>>
>> I don't think so, but it could be, I think the scrolling code is just
>> very inefficient. Feel free to poke things a bit around this, ARM
>> cache management is not my forte.
>
> I think it need ssomething like the code in exynos/soc.c - see
> v7_outer_cache_enable().
>
> Even with the 7 inch it's very slow.

Ok, I'll put looking into this on my TODO list, if someone who is more
knowledge beats me to it I won't complain :)

>>> Also are there instructions for getting an LCD running in U-Boot? I
>>> have an Olimex A20-OLinuxion-MICRO (what a mouthful!) with a 7 inch
>>> display if that matters. I can't find any useful information so far.
>>
>>
>> He he, your in luck I've been working on LCD support the last few days,
>> and I just got the olimex 7" lcd running on olimex boards :)
>>
>> If you use my current wip tree:
>>
>> https://github.com/jwrdegoede/u-boot-sunxi/tree/sunxi-wip
>>
>> And build for the A20-OLinuXino_MICRO-lcd7_defconfig things should
>> just work, assuming you are using the standard olimex 7" lcd with
>> a standard 40 pins pata cable.
>>
>> Note in order for the kernel to take over the fb you need a small
>> kernel patch on top of 3.19, I've attached the patch.
>
> That's great, yes it works!
>
> Looking at the patches, rather than adding new board configs and
> CONFIGs I think it should be device-tree-controlled. Maybe an
> environment variable could hold the display type?

I agree that ultimately this should all move to devicetree as mentioned
in this commit message:

https://github.com/jwrdegoede/u-boot-sunxi/commit/4182ed0c8d037a357161dda63e179340e08adb7e

:)

As for using an environment variable, there is already video-mode env. var support, see
doc/README.video in my tree. I've considered also adding things like the LCD timings to
the environment but they really belong in a devicetree overlay, and if I add support for
them to the environment now I need to keep supporting that in the future. So the plan is
to use Kconfig for now, and move over to dt in the future.

Regards,

Hans