[PATCH] Add framebuffer in BBB

[Christian Mauderer]

On 27/07/2019 21:43, Vijay Kumar Banerjee wrote:
> 
> 
> 
> On Sat, Jul 27, 2019 at 7:37 PM Christian Mauderer <list at c-mauderer.de
> <mailto:list at c-mauderer.de>> wrote:
> 
>     On 26/07/2019 13:41, Christian Mauderer wrote:
>     > On 26/07/2019 13:22, Vijay Kumar Banerjee wrote:
>     >> Hello everyone!
>     >>
>     >> I'm excited to post the following patchset. With this patchset
>     >> I have the framebuffer working in BBB and have tested it with a
>     >> BBB revC with HDMI connected Screen.
>     >>
>     >> This patchset uses mmap and hence it's necessary to apply the
>     >> patche ON TOP OF mmap patch to avoid merge conflict.
>     >>
>     >> In reply to this mail, I'll be attaching a picture of the screen
>     >> where my rectangle drawing application made a nice red rectangle
>     >> on the screen just like in FreeBSD.
>     >>
>     >> Thanks and regards,
>     >> Vijay
>     >>
>     >
>     > Hello Vijay,
>     >
>     > it's great that you now have a working driver. Well done.
>     >
>     > I hadn't had a look at most patches yet and most likely that will
>     need a
>     > bit of time. It's a lot of stuff. Most likely the bigger patches won't
>     > reach the mailing list so maybe adding a link to a branch on your
>     github
>     > repo would be good.
>     >
>     > Note: Please don't send a v2 right now. I'm sure there are more
>     comments
>     > (maybe not only from me). Collect comments for at least one or two
>     days
>     > and create an update afterwards.
>     >
>     > Some notes reading the patch overview:
>     >
>     >> [PATCH 01/10] TDA19988 : Import from FreeBSD
>     >> [PATCH 02/10] TDA19988 : port to RTEMS
>     >> [PATCH 03/10] am335x display drivers: Import from FreeBSD
>     >> [PATCH 04/10] am335x display drivers : Port to RTEMS
>     >> [PATCH 05/10] fbd : Import from FreeBSD
>     >> [PATCH 06/10] fbd : Port to RTEMS
>     >
>     > Is fbd a prerequisite of am335x_lcd? In that case it would have been
>     > better to reorder the patches. As long as every version compiles (to
>     > allow git bisect) I would accept that order too. But as a general rule
>     > prerequisites should be prior to the parts that use it.
>     >
>     >> [PATCH 07/10] VT : Import from FreeBSD
>     >> [PATCH 08/10] VT : Port to RTEMS
>     >
>     > Is the vt still necessary? I think it was an intermediate step to try
>     > whether it's initializing the display. Did you try without it?
>     >
>     >> [PATCH 09/10] TI Pinmux : Import from FreeBSD
>     >> [PATCH 10/10] TI Pinmux : Port to RTEMS
>     >
>     > Again: prerequisite. So they should be one of the first.
>     >
>     > Best regards
>     >
>     > Christian
>     >
> 
>     One general question: When trying the patches, my monitor has been set
>     up as 1440x900 instead of it's native resolution. Did you check whether
>     the resolution on your screen is set correctly?
> 
> It's not setting fb with the "preferred videomode", I can confirm that
> the resolution
> set by FreeBSD and RTEMS is same. 

OK. Sooner or later it might would be good to find out how to set
another resolution. Currently I have the following output:

````
Preferred mode: 1920x1200 @ 60Hz
Number of extension blocks: 1
fb0: detected videomode: 1440x900 @ 60KHz
fbd0 on fb0
````

It's a bit odd that not the preferred mode is used. But if it is the
same for FreeBSD it's OK for a start.

One other problem: I tried to create some solid regions and it seems
that there are a few artefacts. Can you try that on your screen and tell
me whether you get them too? For the code and an image how it looks like
on my screen take a look at
    https://gist.github.com/c-mauderer/051689bb1199caf20a08d9844c44c113

Some of the lines vanished after a few seconds. I think that could be a
memory caching issue.

> 
>     Best regards
> 
>     Christian
>