Beagleboard BSP Framebuffer

Christian Mauderer christian.mauderer at embedded-brains.de
Tue Mar 12 10:59:36 UTC 2019


Am 12.03.19 um 11:35 schrieb Vijay Kumar Banerjee:
> 
> 
> 
> On Tue, 12 Mar 2019 at 15:27, Christian Mauderer
> <christian.mauderer at embedded-brains.de
> <mailto:christian.mauderer at embedded-brains.de>> wrote:
> 
>     Am 12.03.19 um 10:52 schrieb Vijay Kumar Banerjee:
>     >
>     >
>     > On Mon, 11 Mar 2019 at 19:21, Gedare Bloom <gedare at rtems.org
>     <mailto:gedare at rtems.org>
>     > <mailto:gedare at rtems.org <mailto:gedare at rtems.org>>> wrote:
>     >
>     >
>     >
>     >     On Sun, Mar 10, 2019 at 7:31 PM Joel Sherrill <joel at rtems.org
>     <mailto:joel at rtems.org>
>     >     <mailto:joel at rtems.org <mailto:joel at rtems.org>>> wrote:
>     >
>     >         The MINIX license is BSD with advertising clause as I read it.
>     >         That is less preferable to a 2-paragraph BSD license that you
>     >         are likely to find in Freebase. Try there.
>     >
>     >     The license is fine if you find nothing else. I assume Joel meant
>     >     FreeBSD.
>     >
>     >     Study the framebuffers in i386 and raspberrypi code bases.
>     >
>     >
>     > Hello,
>     >
>     > Thanks for the reference, I found the tda19988 driver in
>     freebsd source.
>     > Following the raspberrypi framebuffer, I have made a header file
>     with the 
>     > basic functions to implement. The implementation will be using the 
>     > driver code from the freebsd. 
>     >
>     > What needs to be figured out next is how to use the driver code
>     with rtems,
>     > since the file uses a lot of header files from the freebsd source,
>     how do we
>     > go about integrating it with rtems? Is there any guide on using
>     codes from 
>     > different projects into RTEMS? 
>     >  
>     >
> 
>     Hello Vijay,
> 
>     for FreeBSD we have the libbsd as an easy way to integrate sources and
>     keep them up to date. Although I don't think that we have a framebuffer
>     driver there yet I would expect that it is a good method for that too.
> 
>     Best regards
> 
>     Christian
> 
> Hi
> 
> I cloned the rtems-libbsd and the framer driver is not there. I wonder
> if adding
> this drivers to libbsd is itself a meaty task. Do we need a ticket for
> this ?

The files are copied between FreeBSD and libbsd using a script.
Basically you have to add the files you need to a (new) module in
libbsd.py. After that you can copy files with the freebsd-to-rtems.py.
Please take a look at CONTRIBUTING.md in the rtems-libbsd repo on how to
use the script.

> 
> Also, the driver uses i2c bus driver from FreeBSD source, I see that the
> i2c driver
> is nicely supported in the rtems beagle bsp, how to use the i2c module
> in the bsp,
> with the hdmi framer driver in libbsd ? (I'm a bit confused here :) )
> 

Most likely there will be adaptions necessary here. Either you have to
replace the BSPs driver with the one from FreeBSD or (the method that I
would suggest) you have to isolate the calls in the FreeBSD framebuffer
driver and replace them with RTEMS calls. With some luck, you can just
overwrite some functions for that. But that is one of the points that
would need a more thorough look.

Besides I2C you should have a look at which other subsystems are used.
Every subsystem that isn't ported yet can be more or less work depending
on the interface. Some might can be ported together with the driver
others might have to be replaced by RTEMS versions.

>     >      
>     >
>     >         It is usable in RTEMS though. We just try to avoid pushing the
>     >         advertising requirement
>     >
>     >
>     >
>     >         On Sun, Mar 10, 2019, 12:47 PM Vijay Kumar Banerjee
>     >         <vijaykumar9597 at gmail.com
>     <mailto:vijaykumar9597 at gmail.com> <mailto:vijaykumar9597 at gmail.com
>     <mailto:vijaykumar9597 at gmail.com>>> wrote:
>     >
>     >
>     >
>     >             On Fri, Mar 8, 2019, 12:35 AM Vijay Kumar Banerjee
>     >             <vijaykumar9597 at gmail.com
>     <mailto:vijaykumar9597 at gmail.com> <mailto:vijaykumar9597 at gmail.com
>     <mailto:vijaykumar9597 at gmail.com>>>
>     >             wrote:
>     >
>     >                 Hi,
>     >
>     >                 I was reading up and trying to figure out the steps to
>     >                 achieve this project. Here's
>     >                 what I came up with :
>     >
>     >                 1. BBB uses TD19988 HDMI Framer, so the first step
>     is to
>     >                 get an HDMI output,
>     >                 read EDID info and set the videomode according to the
>     >                 info. After some searching,
>     >                 I found a driver in minix that might be helpful.
>     Is the
>     >                 minix license compatible? 
>     >               
>      (https://github.com/Stichting-MINIX-Research-Foundation/minix/blob/03ac74ede908465cc64c671bbd209e761dc765dc/LICENSE)
>     >
>     >                 2. Set the values of structs from fb.h 
>     >                 3. Write the fb.c using the functions from
>     framebuffer.h
>     >                 ( I'm taking the fb.c in raspberrypi 
>     >                 as example and the bsp-howto as a reference text)
>     >
>     >                 The above list is just an outline and I intend to
>     >                 explore/understand it better and make a
>     >                 proposal out of it.
>     >
>     >                 Does this list make sense to you? 
>     >
>     >                 What am I missing?
>     >
>     >                 I would really appreciate any remarks/comments or
>     >                 details you'd like to add, it will help me
>     understand it
>     >                 better.
>     >
>     >             ping :)
>     >
>     >
>     >                 Thanks,
>     >                 --vijay
>     >
>     >         _______________________________________________
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>     >
> 
>     -- 
>     --------------------------------------------
>     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.



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