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by Electron752
Thu Mar 23, 2017 1:04 pm
Forum: Bare metal, Assembly language
Topic: Powering down the VPU
Replies: 7
Views: 1583

Re: Powering down the VPU

Looks like this could be easier then I thought. Perhaps all I need to do is force an interrupt or exception on the things after moving the vectors.

BTW, the instruction set of this thing is very similar to something I've seen before.
by Electron752
Thu Mar 23, 2017 8:27 am
Forum: Bare metal, Assembly language
Topic: ARM CPU spin table
Replies: 1
Views: 976

ARM CPU spin table

Way back in the very early days of ARM64, someone implemented an armstub that got catted onto to something else. When the boot sequence started the stub, all the ARM cores were identical and the core id was used to sort out which core was what. Part of the stub implemented the spin table that's need...
by Electron752
Thu Mar 23, 2017 8:08 am
Forum: Bare metal, Assembly language
Topic: Powering down the VPU
Replies: 7
Views: 1583

Powering down the VPU

Does the VPU have any power management ability? Essentially I want to power down the VPU or turn off it's clock. Ideally I would want to do this without the VPU being functional(say it's hung or something). Ideally, it would be interesting if it were possible to replace the code that the VPU runs af...
by Electron752
Wed Mar 22, 2017 9:53 pm
Forum: Bare metal, Assembly language
Topic: Open Firmware Alternative
Replies: 1
Views: 1247

Open Firmware Alternative

I'm looking into the possibility of creating a open firmware alternative to the existing firmware. I found an existing project on the web: https://github.com/christinaa/rpi-open-firmware But I'm not sure I agree with some of there design decision/architecture. I really don't want to complete replace...
by Electron752
Wed Mar 22, 2017 7:15 pm
Forum: Bare metal, Assembly language
Topic: VC core vc ARM benchmark
Replies: 33
Views: 5321

VC core vc ARM benchmark

Hi, I found out that the VC core has a open source compiler now. Has anybody every attempted to run any kind of benchmarks that compare the performance of a program compiled for VC vs a program compiled for ARM? I would be curious how the performance of the two differ. It is interested that the VC c...
by Electron752
Wed Mar 22, 2017 7:06 pm
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

Perhaps I should open a different topic: Since the VC core has a free compiler for it now, and it can run arbitrary programs on it own, has anybody done any benchmarks to compare real programs compiled on it vs arm? Which is faster for a given clock speed? I was thinking of the logical extension of ...
by Electron752
Tue Mar 21, 2017 2:10 pm
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

Exactly, which driver are we talking about here. If were talking about VC4(I know that was the original topic), I have no idea. You'll need to send an email to him or contact him on his www.github.com page. That's not really something I know much about and isn't really part of what I'm thinking abou...
by Electron752
Tue Mar 21, 2017 1:42 pm
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

That's interesting... I was kind of hoping that could be accessed from the ARM. I though the VC4 driver was doing some of that already? I've have to read more of dwelch's examples as to exactly how much functionality bootcode.bin gives and how much would need to be written in a replacement for the ....
by Electron752
Tue Mar 21, 2017 1:17 pm
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

BTW, I'm browsing through this guys site and he has a very interesting idea in some of the directories. In some of his examples, he uses bootcode.bin from the standard releases plus custom .elf/.dat replacements. That may well in fact be exactly what I'm looking for. Just use enough of the standard ...
by Electron752
Tue Mar 21, 2017 1:07 pm
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

You know what, I think this dwelch guy is alot closer to what I'm trying to accomplish. I'm not trying to reverse engineer the chip at all. In fact I just want to attempt and it may be beyond my ability to just get a bootstrapper running. I don't really care about those parts of the chip. I'm not in...
by Electron752
Tue Mar 21, 2017 10:46 am
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

Basically what I'm saying boils down to this. The end user should have choices and they should ultimately be the ones making the decision. You use the closed source firmware maybe pay for the codec pack, you get to use the camera or play video with hardware acceleration. But people should have the o...
by Electron752
Tue Mar 21, 2017 10:35 am
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

I'm not saying anything about conspiracies. Some large company needs to dump alot of resources into making something happen, they can't afford to have people start cloning it right away. That's the way the world works and people accept that, including me. If I were to go down this path at all, which...
by Electron752
Tue Mar 21, 2017 8:11 am
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

Since my primary interest has always been embedded, I wonder what it would take to make a very basic firmware and boot loader that didn't support the camera and only a very stripped down no acceleration frame buffer display just for occasional debugging. Say when the thing doesn't boot.
by Electron752
Tue Mar 21, 2017 7:57 am
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

I know what you mean about block boxes. It makes one wonder what exactly is happening that they don't want people to know about.

So I wonder what it takes to get the source to the graphics stack and what exactly a clause 3 BSD license means really?
by Electron752
Tue Mar 21, 2017 7:40 am
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Re: Eric Anholt offically announces support of VC4 without a

Yah, the good news is that display is working now on mainline Linux on the RPI 3. It might not have been quite the way people wanted it to, but it works now. I kind of hope the expander driver gets tossed by the stagging maintainer in upstream. I thought the whole implementation behind it was not th...
by Electron752
Tue Mar 21, 2017 5:26 am
Forum: General discussion
Topic: Eric Anholt offically announces support of VC4 without acces
Replies: 27
Views: 3243

Eric Anholt offically announces support of VC4 without acces

It appears the Eric Anholt has announced support for VC4 on mainline linux without any use of the expander. Sounds like he never needed it all along. http://lists.infradead.org/pipermail/linux-rpi-kernel/2017-March/005945.html BTW, If you build a mainline version of Linux yourself. You might want to...
by Electron752
Wed Mar 08, 2017 1:48 pm
Forum: Graphics, sound and multimedia
Topic: RPI 3 Camera Apps that use V4L support
Replies: 4
Views: 751

Re: RPI 3 Camera Apps that use V4L support

OK, thanks. That's a good list of applications I can use to test with.
Thanks both for answering my question!
by Electron752
Wed Mar 08, 2017 9:22 am
Forum: Graphics, sound and multimedia
Topic: RPI 3 Camera Apps that use V4L support
Replies: 4
Views: 751

Re: RPI 3 Camera Apps that use V4L support

OK, I guess that's a V8 moment.

That's probably good enough to get me going.
by Electron752
Wed Mar 08, 2017 8:06 am
Forum: Graphics, sound and multimedia
Topic: RPI 3 Camera Apps that use V4L support
Replies: 4
Views: 751

RPI 3 Camera Apps that use V4L support

I might be submitting some cleanup work for the V4L kernel module to the upstream Linux kernel. I was wondering if anybody has a brief list of applications that people typically use on the RPI that is known to work well with the V2 camera. I already know about Raspicam but I don't think it uses the ...
by Electron752
Sat Mar 04, 2017 10:48 pm
Forum: Bare metal, Assembly language
Topic: Playing analog audio
Replies: 5
Views: 1113

Re: Playing analog audio

Cool, thanks. I've forked your github version.
by Electron752
Fri Mar 03, 2017 4:14 pm
Forum: Bare metal, Assembly language
Topic: Playing analog audio
Replies: 5
Views: 1113

Re: Playing analog audio

Thanks,

Out of curiosity did you experimentally check the differences between using 8 bit with a high sample rate vs. say 12 bit with a much lower sample rate?
by Electron752
Fri Mar 03, 2017 4:19 am
Forum: Bare metal, Assembly language
Topic: Playing analog audio
Replies: 5
Views: 1113

Re: Playing analog audio

BTW, I'm assuming I can drive the pwm directly off of PLLB or PLLC with a divisor of either 1 or 2 which should give me almost exactly the frequencies I want(either 48KHz or 96KHz) within an error of < 1%.

Am I correct in thinking I can drive the pwm directly off PLLB or PLLC?
by Electron752
Fri Mar 03, 2017 3:33 am
Forum: Bare metal, Assembly language
Topic: Playing analog audio
Replies: 5
Views: 1113

Playing analog audio

I'm doing some thinking into generating some analog audio and I'm thinking about how to generate the correct clocks for the RPI. My first thought is that I would like to play 16 [email protected] audio through the jack, but as I do some number punching I can clearly see that would require a PWM clock rate o...
by Electron752
Thu Mar 02, 2017 6:35 am
Forum: Device Tree
Topic: when and how does the kernel load the modules
Replies: 10
Views: 2926

Re: when and how does the kernel load the modules

That's both good and bad. I was kind of expecting that perhaps a module could have different code sections that get loaded independently. For something like usb or pci, it makes sense though because the bus controller can enumerate the bus without needing to know anything special about the devices i...
by Electron752
Tue Feb 28, 2017 1:52 am
Forum: Device Tree
Topic: when and how does the kernel load the modules
Replies: 10
Views: 2926

Re: when and how does the kernel load the modules

I'm curious how the module loading works for systems such as usb where the devices may or may not be present and can be plugged in some time after boot? I mean the init call needs to run to register the driver with the usb core, but the body of the driver doesn't need to load until the pid/vid of th...

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