Hi, Matteo,I used to know the frame buffer logic well. I wrote most of the old
X style frame buffer logic and have always had an intest in that.. I don't
know what the LVGVL users and Xiaomi have changed, so I am out of date,All that
being said, I would be interested in helping out in any way possible.GregSent
from my Galaxy
-------- Original message --------From: Matteo Golin <[email protected]>
Date: 05/11/25 3:49 pm (GMT-06:00) To: [email protected] Subject: Re: RPI
4B Roadmap Hi all,Despite a relatively small bug with transfer size limits, the
RPi4B microSDcard support is basically done. This is largely in part to how
simple it ison NuttX to write a lower-half SDIO implementation and have things
justwork, which is incredible :)I now (ambitiously) want to set my eyes on
graphics. It turns out thatrendering with a framebuffer is actually quite easy,
but very CPUintensive. I'm going to need to figure out how to get at the GPU
properly. *Myquestion is: *is anyone familiar with examples on how to implement
thenecessary "lower-half" for the NuttX graphics library? I.e.
whatfunctions/drivers I would need to get written to allow the basic
windowingdisplay manager & LVGL to work on the HDMI outputs of the Pi? I
havebriefly read the docs about the window manager and saw that there is
aframebuffer char driver that can be implemented, but I'm not sure how wellthat
scales to decent graphics. I suppose this is relatively unchartedterritory on
an RTOS designed mainly with LCDs in mind as the only graphics(?). If anyone
has implemented graphics support for a device before and canlet me know a few
source files to look at, that would be great!My main goal is essentially to get
decently fast graphics going, since oncethat's done and some USB HID device
support is set up, I can port DOOM toNuttX :)Thanks,MatteoOn Wed, Oct 22, 2025
at 12:32 PM Matteo Golin <[email protected]>wrote:> Thanks Tomek! That
would be a good resource.>> On Wed, Oct 22, 2025 at 7:29 AM Tomek CEDRO
<[email protected]> wrote:>>> OpenBSD 7.8 has been just released and it has
official support for rPI>> 5 with all sorts of peripherals.. maybe this is the
new source to look>> for drivers code? :-)>>>>
https://ftp.openbsd.org/pub/OpenBSD/7.8/arm64/INSTALL.arm64>>>>
https://cvsweb.openbsd.org/src/>>>> Have a good day :-)>> Tomek>>>> On Tue, Sep
16, 2025 at 5:22 PM Matteo Golin <[email protected]>>> wrote:>> >>> >
Thanks Alan! Maybe I will reach out to Arasan, could have more luck than>> >
with Broadcom, but I doubt it.>> >>> > I'll take a look at these documents!>>
>>> > Thanks again,>> > Matteo>> >>> > On Tue, Sep 16, 2025, 11:00 AM Alan C.
Assis <[email protected]> wrote:>> >>> > > Hi Matteo,>> > >>> > > Please that a
look:>> > > https://www.arasan.com/products/sd-emmc/sdio-3-0-device/>> > >>> >
> There is an option to Download (request) the Datasheet from that>> page,
but>> > > you can access it directly here:>> > >>> > >>>
https://www.arasan.com/wp-content/uploads/2016/05/3MCR-Total-IP-Solution.pdf>>
> >>> > > This document is more about the IP core details, but could give you>>
more>> > > understanding about internal block of the SDIO controller (its
FIFO,>> > > initialization diagram, etc)>> > >>> > > You can also try to find
the original>> > > SD3.0_Host_AHB_eMMC4.4_Usersguide_ver5.9_jan11_10.pdf cited
in>> Raspberry>> > > documentation.>> > >>> > > BR,>> > >>> > > Alan>> > >>> >
>>> > >>> > > On Tue, Sep 16, 2025 at 11:17 AM Matteo Golin
<[email protected]>> >>> > > wrote:>> > >>> > > > Hi Alan,>> > > >>> > > >
Thank you for the tips! Yes, SDIO looks pretty involved compared to>> SPI>> > >
or>> > > > I2C. I'll try reading the specification like you suggested.>> > >
>>> > > > The BCM2711 datasheet doesn't document it at all, however the EMMC>>
> > > interface is supposedly the exact same from the BCM2835 and the>>
registers>> > > > there are at least documented. All I know is that it is using
an>> > > interface>> > > > by Arasan. I'm not as familiar with NuttX, but if
this at all looks>> like>> > > > something that's already been supported,
please let me know. In the>> > > > meantime, I'll look through the SDIO
implementations to check:>> > > >>> > >>>
https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf>> >
> > (page 65)>> > > >>> > > > Thanks again!>> > > > Matteo>> > > >>> > > > On
Tue, Sep 16, 2025 at 9:49 AM Alan C. Assis <[email protected]>>> wrote:>> > >
>>> > > > > HI Matteo,>> > > > >>> > > > > I implemented the SDIO support for
LPC43 some years ago and what>> helped>> > > > me>> > > > > most was reading
the SD/MMC specification, the LPC43 reference>> manual>> > > and>> > > > >
enabling the NuttX SD/MMC debug messages.>> > > > >>> > > > > There are many
details to take care of: clock enable for the>> > > controller,>> > > > >
interrupts, pins configuration, etc.>> > > > >>> > > > > Unfortunately, the
BCM2711 doc is not good. You can start>> verifying the>> > > > > registers,
maybe it is based on some SD/MMC core IP already>> supported>> > > by>> > > > >
NuttX.>> > > > >>> > > > > BR,>> > > > >>> > > > > Alan>> > > > >>> > > > >>> >
> > >>> > > > > On Mon, Sep 15, 2025 at 6:34 PM Matteo Golin <>>
[email protected]>>> > > > > wrote:>> > > > >>> > > > > > Hi everyone,>> >
> > > >>> > > > > > Now that I2C has been tackled, I am moving on to SDIO>>
interfaces so>> > > the>> > > > > SD>> > > > > > card can be interacted with
from NuttX.>> > > > > >>> > > > > > The NuttX SDIO documentation is a little
bare, and I'm not the>> most>> > > > > > familiar with SDIO. Does anyone have
any recommendations for>> > > > > > implementations to look at (besides the
STM32 one that is>> linked in>> > > the>> > > > > > docs), resources to read
(any blog posts from when you ported>> SDIO)>> > > or>> > > > > > advice in
general? It would be much appreciated.>> > > > > >>> > > > > > Thank you,>> > >
> > > Matteo>> > > > > >>> > > > > > On Fri, Sep 5, 2025, 11:15 AM Matteo Golin
<>> [email protected]>>> > > > > wrote:>> > > > > >>> > > > > > > Got
another response from my earlier request to Raspberry Pi>> > > through>> > > >
> > their>> > > > > > > website:>> > > > > > >>> > > > > > > Hi Matteo>> > > >
> > >>> > > > > > >>> > > > > > >>> > > > > > >> Thanks for getting in touch.
We don't actually have any more>> > > > > > >> documentation that we can
release on this. My usual>> recommendation>> > > > is>> > > > > > for>> > > > >
> >> SW people to take a look at the Linux drivers to get a closer>> > > > > >
understanding>> > > > > > >> of how the HW works. Not ideal, but the best I can
offer.>> > > > > > >>> > > > > > >>> > > > > > > So I guess everyone is telling
us the same thing!>> > > > > > >>> > > > > > >>> > > > > > > On Mon, Sep 1,
2025 at 3:49 PM Tomek CEDRO <[email protected]>>> > > wrote:>> > > > > > >>> > >
> > > >> Sure! Public now :-)>> > > > > > >> Tomek>> > > > > > >>>> > > > > >
>> On Mon, Sep 1, 2025 at 9:24 PM Matteo Golin <>> > > [email protected]>>
> > > >>> > > > > > >> wrote:>> > > > > > >> >>> > > > > > >> > I have
populated the RPi 4B project with some starting>> issues to>> > > > > >
tackle>> > > > > > >> for>> > > > > > >> > the 4B implementation. I see that
the project is marked as>> > > > private;>> > > > > is>> > > > > > >> > there
any way to make it visible to potential contributors>> just>> > > > > >
visiting>> > > > > > >> > the GitHub page? I think if they can see a list of
issues>> in one>> > > > > place>> > > > > > >> when>> > > > > > >> > they go to
the page it might help.>> > > > > > >> >>> > > > > > >> > Thanks,>> > > > > >
>> > Matteo>> > > > > > >> >>> > > > > > >> > On Mon, Sep 1, 2025 at 3:02 PM
Tomek CEDRO <>> [email protected]>>> > > > > wrote:>> > > > > > >> >>> > > > > >
>> > > Thank you Linguini, good luck and have fun! :-)>> > > > > > >> > >
Tomek>> > > > > > >> > >>> > > > > > >> > > On Mon, Sep 1, 2025 at 8:48 PM
Matteo Golin <>> > > > > [email protected]>> > > > > > >>> > > > > > >> >
> wrote:>> > > > > > >> > > >>> > > > > > >> > > > To update the community,
we've been told by Gordon>> that the>> > > Pi>> > > > > > >> Foundation>> > > >
> > >> > > > doesn't have any documentation for the chip beyond>> what was>> >
> > > > written>> > > > > > >> in>> > > > > > >> > > the>> > > > > > >> > > >
peripheral datasheet. Broadcom themselves has written>> the>> > > > Linux>> > >
> > > >> drivers>> > > > > > >> > > and>> > > > > > >> > > > Raspberry Pi has
only made some slight bug fixes, etc.>> We've>> > > > > been>> > > > > > >> > >
suggested>> > > > > > >> > > > to read the source to discover undocumented>> >
> > > > registers/configuration>> > > > > > >> > > options.>> > > > > > >> > >
>>> > > > > > >> > > > I plan to still continue with the port until the>>
feature set>> > > > on>> > > > > > >> NuttX is>> > > > > > >> > > > equal or
greater to what is available on QNX. I at>> least>> > > want>> > > > to>> > > >
> > get>> > > > > > >> > > > Ethernet and some graphics running after the
base>> peripheral>> > > > set>> > > > > > >> (I2C,>> > > > > > >> > > SPI,>> >
> > > > >> > > > UART) are supported.>> > > > > > >> > > >>> > > > > > >> > > >
Matteo>> > > > > > >> > > >>> > > > > > >> > > > On Sun, Aug 31, 2025 at 6:10
PM Matteo Golin <>> > > > > > >> [email protected]>>> > > > > > >> > >
wrote:>> > > > > > >> > > >>> > > > > > >> > > > > Very interesting Sebastian.
I got that impression>> from>> > > > > Broadcom>> > > > > > >> when I>> > > > >
> >> > > was>> > > > > > >> > > > > initially trying to port NuttX to the Pi.
The>> inability to>> > > > > > submit>> > > > > > >> > > forms on>> > > > > >
>> > > > > their website seems like it might be by design...>> > > > > > >> > >
> >>> > > > > > >> > > > > I'm hopeful the Raspberry Pi Foundation will have>>
> > something>> > > > > more>> > > > > > >> for>> > > > > > >> > > us to>> > >
> > > >> > > > > work with, they seem more positive to FOSS.>> Otherwise I>> >
> will>> > > > > > still>> > > > > > >> > > continue>> > > > > > >> > > > >
with reverse engineering until at least the point>> where>> > > the>> > > > > >
>> > > functionality>> > > > > > >> > > > > driver-wise is on par with QNX.>> >
> > > > >> > > > >>> > > > > > >> > > > > On Sun, Aug 31, 2025, 10:46 AM Tomek
CEDRO <>> > > > [email protected]>>> > > > > > >> wrote:>> > > > > > >> > > >
>>> > > > > > >> > > > >> James Dougherty contacted us with Gordon>>
Hollingworth>> > > from>> > > > > > >> Raspberry>> > > > > > >> > > > >> Pi
Foundation recently :-) We are waiting for>> response>> > > :-)>> > > > I>> > >
> > > >> really>> > > > > > >> > > > >> hope we can get some sort of
documentation and/or>> code>> > > > > samples>> > > > > > to>> > > > > > >> > >
> >> write high quality NuttX port for the big>> raspberries :-)>> > > > > > >>
> > > >>>> > > > > > >> > > > >> Open-Source matters even more in this crazy
world.>> Thanks>> > > > for>> > > > > > >> > > > >> interesting article
Sebastien! Personally I think we>> > > should>> > > > > > >> focus only>> > > >
> > >> > > > >> on vendors that support Open-Source. What is the>> reason>> > >
for>> > > > > > >> bumping>> > > > > > >> > > > >> sales for companies that in
the end can sue you for>> > > > > reversing?>> > > > > > :D>> > > > > > >> > >
> >>>> > > > > > >> > > > >> Have a good day folks :-)>> > > > > > >> > > > >>
Tomek>> > > > > > >> > > > >>>> > > > > > >> > > > >>>> > > > > > >> > > > >>>>
> > > > > >> > > > >> On Sun, Aug 31, 2025 at 10:15 AM Sebastien Lorquet <>> >
> > > > >> > > [email protected]>>> > > > > > >> > > > >> wrote:>> > > > > >
>> > > > >> >>> > > > > > >> > > > >> > Hello,>> > > > > > >> > > > >> >>> > >
> > > >> > > > >> > I just found this interesting document:>> > > > > > >> > >
> >> >>> > > > > > >> > > > >> >>> > > > > > >> > > > >>>> > > > > > >> > >>> >
> > > > >>>> > > > > >>> > > > >>> > > >>> > >>>
https://fastcode.io/2025/08/30/the-69-billion-domino-effect-how-vmwares-debt-fueled-acquisition-is-killing-open-source-one-repository-at-a-time/>>
> > > > > >> > > > >> >>> > > > > > >> > > > >> > In a summary, if you expect
anything cool from>> > > broadcom:>> > > > > > dont.>> > > > > > >> > > > >>
>>> > > > > > >> > > > >> > go go go reverse engineering!>> > > > > > >> > > >
>> >>> > > > > > >> > > > >> > Sebastien>> > > > > > >> > > > >> >>> > > > > >
>> > > > >> >>> > > > > > >> > > > >> > On 8/29/25 15:37, Tomek CEDRO wrote:>>
> > > > > >> > > > >> > > No response from #infra@slack, I just sent>>
request>> > > to>> > > > > > >> > > > >> > > [email protected] mailing list
maybe>> someone can>> > > > > reply>> > > > > > >> over>> > > > > > >> > >
there>> > > > > > >> > > > >> > > :-)>> > > > > > >> > > > >> > >>> > > > > >
>> > > > >> > >>> > > > > > >>>>
https://lists.apache.org/thread/n9y5vrvjm23npwgbr45f7zq5ys5l8dok>> > > > > > >>
> > > >> > >>> > > > > > >> > > > >> > > We should also know the official
stance from>> Broadcom>> > > > and>> > > > > > RPI>> > > > > > >> > > > >>
Foundation :-)>> > > > > > >> > > > >> > >>> > > > > > >> > > > >> > > Thanks
:-)>> > > > > > >> > > > >> > > Tomek>> > > > > > >> > > > >> > >>> > > > > >
>> > > > >> > > On Thu, Aug 28, 2025 at 9:35 PM Tomek CEDRO <>> > > > > > >>
[email protected]>>> > > > > > >> > > wrote:>> > > > > > >> > > > >> > >> I just
asked question at #asfinfra / slack,>> maybe>> > > > > someone>> > > > > > >>
can>> > > > > > >> > > help>> > > > > > >> > > > >> > >> there or recommend
someone who can, waiting for>> > > > response>> > > > > > :-)>> > > > > > >> >
> > >> > >>>> > > > > > >> > > > >> > >> For a good start you can contact
Broadcom and>> > > > > RaspberryPi>> > > > > > >> > > Foundation,>> > > > > >
>> > > > >> > >> introduce yourself as Apache NuttX RTOS>> developer>> > >
that>> > > > > > want>> > > > > > >> to>> > > > > > >> > > port>> > > > > > >>
> > > >> > >> NuttX to rPI boards, and just ask if>> DataSheets are>> > > > > >
>> available>> > > > > > >> > > :-) We>> > > > > > >> > > > >> > >> will know
then first hand if this is possible>> or are>> > > > > there>> > > > > > >>
any>> > > > > > >> > > > >> > >> problems / requirements :-)>> > > > > > >> > >
> >> > >>>> > > > > > >> > > > >> > >> You can ask for 4B and probably Zero-2W
SoC>> > > > > documentation>> > > > > > >> these>> > > > > > >> > > seems>> > >
> > > >> > > > >> > >> most popular nowadays :-)>> > > > > > >> > > > >> > >>>>
> > > > > >> > > > >> > >> Thanks :-)>> > > > > > >> > > > >> > >> Tomek>> > >
> > > >> > > > >> > >>>> > > > > > >> > > > >> > >>>> > > > > > >> > > > >> >
>>>> > > > > > >> > > > >> > >> On Thu, Aug 28, 2025 at 8:45 PM Matteo Golin
<>> > > > > > >> > > [email protected]>>> > > > > > >> > > > >> wrote:>> >
> > > > >> > > > >> > >>> Hi Tomek,>> > > > > > >> > > > >> > >>>>> > > > > >
>> > > > >> > >>> Thanks so much! I actually hadn't thought of>> that,>> > > >
> maybe>> > > > > > we>> > > > > > >> > > could>> > > > > > >> > > > >> ask
for>> > > > > > >> > > > >> > >>> help from the foundation. Do you know who's>>
the>> > > best>> > > > > > point>> > > > > > >> of>> > > > > > >> > > > >>
contact for>> > > > > > >> > > > >> > >>> that?>> > > > > > >> > > > >> > >>>>>
> > > > > >> > > > >> > >>> I know Linux must have received the>> datasheets
to>> > > > make>> > > > > > >> > > Raspberry Pi>> > > > > > >> > > > >> OS.
No>> > > > > > >> > > > >> > >>> offence to NuttX, but Linux is pretty
popular>> in>> > > > > > >> comparison. If>> > > > > > >> > > > >> Broadcom
or>> > > > > > >> > > > >> > >>> Raspberry Pi would release us some>>
information that>> > > > > would>> > > > > > >> be an>> > > > > > >> > > > >>
immense>> > > > > > >> > > > >> > >>> help. I suspect there was some kind of
deal>> with>> > > the>> > > > > > Linux>> > > > > > >> group>> > > > > > >> > >
> >> but I have>> > > > > > >> > > > >> > >>> no idea. I believe even QNX
didn't have>> access to>> > > the>> > > > > > >> datasheets>> > > > > > >> > >
> >> and rather>> > > > > > >> > > > >> > >>> just reverse engineered the Linux
drivers.>> > > > > > >> > > > >> > >>>>> > > > > > >> > > > >> > >>> Matteo>> >
> > > > >> > > > >> > >>>>> > > > > > >> > > > >> > >>> On Thu, Aug 28, 2025,
12:42 PM Tomek CEDRO <>> > > > > > >> [email protected]>>> > > > > > >> > > > >>
wrote:>> > > > > > >> > > > >> > >>>>> > > > > > >> > > > >> > >>>> On Tue, Aug
26, 2025 at 10:05 PM Matteo>> Golin <>> > > > > > >> > > > >>
[email protected]>>> > > > > > >> > > > >> > >>>> wrote:>> > > > > > >> >
> > >> > >>>>> I2C still needs some work unfortunately.>> > > However, I>> > >
> > > agree>> > > > > > >> > > with you>> > > > > > >> > > > >> > >>>>>
generally. Personally, I think HDMI,>> networking>> > > > > > >> (including>> >
> > > > >> > > WiFi>> > > > > > >> > > > >> and BLE)>> > > > > > >> > > > >> >
>>>>> and some kind of interaction with storage>> (eMMC>> > > or>> > > > SD>> >
> > > > >> card)>> > > > > > >> > > are>> > > > > > >> > > > >> the most>> > >
> > > >> > > > >> > >>>>> important. Unfortunately, those are likely>> going>>
> > to>> > > > > be>> > > > > > >> the>> > > > > > >> > > most>> > > > > > >> >
> > >> difficult>> > > > > > >> > > > >> > >>>>> because of the lack of
documentation on the>> > > > > > peripherals.>> > > > > > >> It is>> > > > > >
>> > > > >> definitely>> > > > > > >> > > > >> > >>>>> not an impossible task,
but it will be>> > > challenging.>> > > > > > >> Hence my>> > > > > > >> > > >
>> request for>> > > > > > >> > > > >> > >>>>> creating the new project
roadmap, so maybe>> some>> > > > > > >> discoveries>> > > > > > >> > > can be>>
> > > > > >> > > > >> > >>>>> documented there and more eyes can get on>> the
RPi>> > > > > > >> > > implementation.>> > > > > > >> > > > >> > >>>> The lack
of documentation is a real pain, and>> > > known>> > > > > > issue>> > > > > >
>> for>> > > > > > >> > > > >> years in>> > > > > > >> > > > >> > >>>> many
areas, but some vendors are especially>> famous>> > > > for>> > > > > > >>
that.>> > > > > > >> > > > >> > >>>>>> > > > > > >> > > > >> > >>>> Considering
someone wants to create>> Open-Source>> > > > > drivers>> > > > > > >> for>> >
> > > > >> > > free>> > > > > > >> > > > >> and>> > > > > > >> > > > >> > >>>>
bring customers to the vendor.>> > > > > > >> > > > >> > >>>>>> > > > > > >> >
> > >> > >>>> Maybe we could ask Apache Foundation for>> help in>> > > > > >
obtaining>> > > > > > >> > > required>> > > > > > >> > > > >> > >>>>
datasheets? :-)>> > > > > > >> > > > >> > >>>>>> > > > > > >> > > > >> > >>>>
-->> > > > > > >> > > > >> > >>>> CeDeROM, SQ7MHZ,
http://www.tomek.cedro.info>> > > > > > >> > > > >> > >>>>>> > > > > > >> > > >
>> > >>>> > > > > > >> > > > >> > >>>> > > > > > >> > > > >> > >> -->> > > > >
> >> > > > >> > >> CeDeROM, SQ7MHZ, http://www.tomek.cedro.info>> > > > > > >>
> > > >> > >>> > > > > > >> > > > >> > >>> > > > > > >> > > > >>>> > > > > > >>
> > > >>>> > > > > > >> > > > >>>> > > > > > >> > > > >> -->> > > > > > >> > >
> >> CeDeROM, SQ7MHZ, http://www.tomek.cedro.info>> > > > > > >> > > > >>>> > >
> > > >> > > > >>> > > > > > >> > >>> > > > > > >> > >>> > > > > > >> > >>> > >
> > > >> > > -->> > > > > > >> > > CeDeROM, SQ7MHZ,
http://www.tomek.cedro.info>> > > > > > >> > >>> > > > > > >>>> > > > > > >>>>
> > > > > >>>> > > > > > >> -->> > > > > > >> CeDeROM, SQ7MHZ,
http://www.tomek.cedro.info>> > > > > > >>>> > > > > > >>> > > > > >>> > > >
>>> > > >>> > >>>>>>>>> -->> CeDeROM, SQ7MHZ, http://www.tomek.cedro.info>>>
