Hi Sergio,

On Fri, 4 Dec 2020 at 13:31, Sergio Sota <[email protected]> wrote:
>
> Dear all,
>
> I'm building a linux system for the Olimex A13SOM module. This little module 
> comes
> with the Allwinner A13 SOC. In the past we have been using other modules with 
> the
> Allwinner A20 SOC and the old sunxi-linux kernel in order to have support for 
> all
> the SOC peripherals (as the Video Engine decoder, Mali GPU, etc)
>
> This time we would like to use a mainline kernel, taking into account that by 
> now
> almost all peripherals are supported in mainline. We have had luck tunning 
> device
> tree (as we were used to use .fex files) and by now we can have Ethernet over 
> SPI,
> Can interface over SPI, ALSA audio output, LCD RGB video output, Cryto engine 
> to
> generate fast entropy, OpenGL ES support (thanks to LIMA driver and Mesa3d 
> libs)
> and so on... but we would like also to have video decoding support.
>
> We have turned on the frontend, backend, video engine in the device tree, 
> build
> the kernel with Cedrus V4L M2M driver, libva_vl42_request and 
> v4l2_request_test.
> (and also set the CMA memory allocation, environment variables, etc)
>
> Using vainfo everything is ok, the linux driver-libva request part works, but 
> then
> we check with v4l2_request_test utility and it fails as there is no DRM 
> support on
> our system. We have on the system /dev/video0 and /dev/media0 but no 
> /dev/dri/card0
> device (in fact we selected the linux sun4i-drm driver but no message appers 
> on the
> boot sequence regarding this, even when build as module it happens nothing...)
>
> We have checked the Cedrus driver information and appears to be no support 
> for the
> DRM plane in A13 SOC (broken/missing) and as I understand that means that 
> part of
> the picture composing work should be done by software (and that's not 
> reliable)
>
> My question is: is there DRM plane support for A13 SOC? (as time goes on I 
> checked
> there has been work done in the mainline kernel and fixes made) Then, in case 
> of no
> support, are there plans to add this support in the future? and finally, 
> could we
> play video files without this DRM support? by what means?

Sorry I can't help you a lot on this.
I don't know if the wiki is up to date for this.
But note that A13 is similar to R8 => C.H.I.P Computer.
All stuff you found on R8 will be the same for A13.

Have a look at the R8 CHIP device-tree.
https://elixir.bootlin.com/linux/latest/source/arch/arm/boot/dts/sun5i-r8-chip.dts

And check that you have a correct TCON description in your dt.
If you can, post your device-tree.
And don't forget to reply if you make it works :)

Regards,
Clement


>
> Thanks in advance for your help and your time, your team have made a wonderful
> work. I also apologize for my poor English, and for writing this email as 
> maybe this is
> not the proper way to issue this questions, but didn't know other way
>
> Best Regards,
> Sergio Sota
>
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