[U-Boot] lcd-console / display rotation

[Nikita Kiryanov <nikita@compulab.co.il>]

Hi Hannes,

On 03/03/2015 12:31 PM, Hannes Petermaier wrote:
>>
>> +Anatolij, Nikita
>>
>> Hi,
> Hi,
> many thanks for response.
>
>>
>> On 2 March 2015 at 03:12, Hannes Petermaier
>> <Hannes.Petermaier@br-automation.com> wrote:
>>> Hello everybody,
>>>
>>> A short question about lcd-console:
>>>
>>> Today u-boot only supports a 'linear framebuffer', meaning the next
> pixel
>>> of a character is allways right after left and the framebuffer address
> is
>>> incrementing.
>>> We call this the display is mounted with 0? rotation.
>>>
>>> In some cases we have a rotated display.
>>> Maybe rotated by 90? to have portrait mode or even 180? due to
> mechanical
>>> issues.
>>>
>>> My question is:
>>> Is anybody currently working around this, having rotated display ?
>>> If not so, i would like start a implementation.
>>>
>>> 180? is quite easy, we only need to add some offset (total len of
>>> framebuffer) to our framebuffer base address and do -- instead ++ for
>>> drawing characters. Font can be reused.
>>>
>>> In the other cases, 90? and 270? it will maybe a bit tricky. I think a
>>> ?rotated font? is also necessary.
>>>
>>> Of course we have to think about the other functions like scroll
> up/down.
>>
>> I don't know of anything, but it sounds useful.
> Okay, Anatolij doesn't also know anything that there is something going
> on.
> I will start to form some ideas how to implement such feature.
>
>>
>> Also I wonder if some hardware has support for this?
> "Support" is the wrong word, sometimes the the lcd is mechanical built in
> rotated and the logical start of the framebuffer isn't as usual at
> top-left, rather it it bottom-right - means rotated by 180?.
>>
>> Nikita (on CC) is tidying up this part of U-Boot so get in touch with
> him.
> Nikita, whats your opinion around that ?

Sounds like a useful feature. I do not anticipate much changes to lcd_console.c
in the near future (not until I try to merge video console with the lcd console
anyway), so for now you can work with it fairly uninterrupted. I only ask that
you avoid adding platform specific code to it. The only platform specific thing
in there right now is a mention of panel_info, and that should disappear soon
as well (replaced with a function call).

-- 
Regards,
Nikita Kiryanov