[PATCH 4/5] sun7i: add support for Micronova srl s027_3 board

[Giulio Benetti <giulio.benetti@benettiengineering.com>]

Hi Andre,

On 2/19/21 12:37 PM, Andre Przywara wrote:
> On Fri, 19 Feb 2021 11:12:08 +0100
> Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:
> 
> Hi,
> 
>> On 2/19/21 2:44 AM, Andre Przywara wrote:
>>> On Fri, 19 Feb 2021 00:26:19 +0100
>>> Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:
>>>
>>> Hi Giulio,
>>>    
>>>> From: Giulio Benetti <giulio.benetti@micronovasrl.com>
>>>>
>>>> Add support for Micronova srl s027_3 board by adding new vendor/board
>>>> folders and using in local Makefile the already present
>>>> board/sunxi/Makefile. The reason is that s027_3 needs a pin to be asserted
>>>> to enable lcd before setting controller up and sunxi board doesn't provide
>>>> a way to do this customization.
>>>
>>> Have you tried CONFIG_VIDEO_LCD_POWER?
>>
>> Yes, I already use that for DISPONOFF.
> 
> So what are these pins for, exactly? Backlight? A regulator to provide
> power to the LCD?

It's the power rail for LCD.

> If you grep for "gpio.CONFIG" in sunxi_display.c, there are more GPIOs
> that we set, for various reasons. Can you pick some from there, and set
> them in your defconfig?

Unfortunately my LCD_PWR drives a P-MOS so it must be inverted, while 
LCD0_DISPONOFF can be meant as a lcd reset.

So I introduce CONFIG_VIDEO_LCD_POWER_ACTIVE_LOW for my board to work
locally.

Would it make sense to send a patch for this for supporting my board?
Or do I wait for you patchset [1] to be applied?

>>> I am strongly against introducing per-board code files, and we
>>> definitely won't introduce them just for one GPIO.
>>
>> I knew it was a strange hack, but I have 2 different pins to be set high
>> before init video controller. Another idea that comes into my mind is to
>> handle CONFIG_VIDEO_LCD_POWER as a gpio list and iterate/enable, what
>> about that?
> 
> Do you really need *two* pins to switch the LCD power supply?

I've messed up names, I need only one pin for LCD power supply(the on 
with P-MOS) but another to enable it(DISPONOFF). But here the problem 
was that LCD power supply is active low.

> If yes,
> this might be an option. But I guess at this point we want to go more a
> DT route.

Yes, agree.

> Speaking of which, I don't see any video output device in the DT, I
> guess you just rely on simplefb.

Yes, simplefb for u-boot while...

> But given that there is no bridge or
> it seems to be transparent, at least, you might be able to describe
> this in the DT as well, so Linux can use its own display driver?

for Linux I use 4 different fdt overlays using fe,be,tcon and simple-panel.

> Then we might be able to find a more sustainable solution, based on
> pins in the DT.

Yes

> 
> Cheers,
> Andre
> 
> P.S. Can you please try to apply

[1]:

> https://patchwork.ozlabs.org/project/uboot/patch/20210205010748.2646-1-andre.przywara at arm.com/
> This would be merged around the same time, and I am curious if this
> still works with an LCD.

For sure I will, I was waiting for this and I've also started to port it 
a bit but I have not much time and then you added a patch. I'm going to 
test it and report. If it doesn't work I'll try to fix it for having 
s027_3 board added using DT then.

Best regards!
-- 
Giulio Benetti
Benetti Engineering sas

> 
>>
>>>> Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
>>>> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
>>>
>>> Please choose one email address, there is no point in having two
>>> S-o-b's from the same person.
>>
>> I missed this as well as the repeated patch in patchset.
>>
>> Thank you
>> Best regards
>