BBB Framebuffer : Need Ideas.

[Vijay Kumar Banerjee]

On Wed, Jul 10, 2019 at 12:40 PM Christian Mauderer <
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.

> Best regards
>
> Christian
> --
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>
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