BBB Framebuffer : Need Ideas.

[Christian Mauderer]

On 10/07/2019 12:38, Vijay Kumar Banerjee wrote:
> 
> 
> On Wed, Jul 10, 2019 at 12:40 PM Christian Mauderer
> <christian.mauderer at embedded-brains.de
> <mailto:christian.mauderer at embedded-brains.de>> wrote:
> 
>     On 09/07/2019 21:13, Vijay Kumar Banerjee wrote:
>     > Hello all, 
>     >
>     > First the status :
>     > * The fbd has been ported and it's attaching with the fb0 devie.
>     There's
>     >    an fb0 device entry created. 
>     > * In the following commit I have added mmap to libbsd. This works
>     like a
>     > wrapper to the mmap in cpukit
>     >
>     : https://github.com/thelunatic/rtems-libbsd/commit/a8fc3b2b6840465029a000cc4169e9efbd551097
>     >
>     > Blocker : 
>     > * After the fb0 is created and mmap is added, I don't see anything on
>     >   the screen. From the FreeBSD, it seemed like the VT driver is needed
>     > and that is responsible for turning on the screen. So I have ported a
>     > minimal version of the VT with only the initialization and
>     allocate parts:
>     >
>     https://github.com/thelunatic/rtems-libbsd/commit/95279e116717973525b581ae2e9550d1d3b8e1ba
>     >
>     > But even after porting the VT driver which initializes well ( As the
>     > message during booting says). I don't see anything on the screen.
>     > I need some ideas on what is missing or how to debug this. 
>     >
>     > The app I'm using to test framebuffer is pushed here :
>     > https://github.com/thelunatic/rtems-bbb/tree/master/apps/fb-sample
>     >
>     > Any idea regarding this is greatly appreciated.
>     >
>     > Thanks,
>     > Vijay
>     >
> 
>     Hello Vijay,
> 
>     did you have a look at the SPI of the HDMI framer? What is it used for
>     according to the data sheet? Is it necessary for the driver?
> 
> Hi,
> From the datasheet, it seems that the SPI1_CS0 and SPI1_D0 pins are 
> configured as I2S interface for the audio. I think this is not necessary 
> and it is enabled only for a few selected resolutions that support audio. 
> 
>     From our chat discussions and my own tests I know that the screen is
>     still not receiving a signal. So I would assume some quite basic
>     problem. If your new mmap wouldn't work, you should still get at least a
>     black screen.
> 
> I was also hoping that VT will do the initialization and turn the screen On.
> There might be something useful that I omitted during the porting. If you 
> can please review the commit, I can send it in the devel.

I think in this case it's enough on your github repo.

I haven't found anything yet. I'll try to have a more detailed look as
soon as possible. But I'll be busy with some other topics today
(including the evening). So most likely I can't tell much till tomorrow.

You might want to have a look whether you find some documentation for
the graphics IP core in the TI chip. It could be interesting to have
some documentation to see the basic steps. Maybe this gives a hint. An
alternative could be to look at some other drivers (Linux, maybe U-Boot
or some embedded systems if there is one) to find out something more.
There should be some sequence for the setup. If you know that sequence
you can try to find it in the libbsd driver and see whether all steps
are done.

> 
>     Best regards
> 
>     Christian
>     -- 
>     --------------------------------------------
>     embedded brains GmbH
>     Herr Christian Mauderer
>     Dornierstr. 4
>     D-82178 Puchheim
>     Germany
>     email: christian.mauderer at embedded-brains.de
>     <mailto:christian.mauderer at embedded-brains.de>
>     Phone: +49-89-18 94 741 - 18
>     Fax:   +49-89-18 94 741 - 08
>     PGP: Public key available on request.
> 
>     Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
> 

-- 
--------------------------------------------
embedded brains GmbH
Herr Christian Mauderer
Dornierstr. 4
D-82178 Puchheim
Germany
email: christian.mauderer at embedded-brains.de
Phone: +49-89-18 94 741 - 18
Fax:   +49-89-18 94 741 - 08
PGP: Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.