Raspberry Pi 4 and VideoCore VI

Is it supported?

I couldn't find that detailed of specs on the VideoCore VI but it seems like it's suppose to be a lot faster.

[wimrijnders]

You can't find any specs because they aren't released (yet, hopefully).

The VC6 isn't that much faster; it has a higher clock rate and more efficient design, so that there are less instructions stalls in the pipeline. However, the number of QPU's has been brought down to 8 from 12.

This results in a significant but slight performance increase:

VideoCore IV @ 250MHz: 250 [MHz] x 3 [slice] x 4 [qpu/slice] x 4 [processor] x 2 [op/clock] = 24 Gflop/s
VideoCore IV @ 300MHz: 300 [MHz] x 3 [slice] x 4 [qpu/slice] x 4 [processor] x 2 [op/clock] = 28.8 Gflop/s
VideoCore VI @ 500MHz: 500 [MHz] x 2 [slice] x 4 [qpu/slice] x 4 [processor] x 2 [op/clock] = 32 Gflop/s

Source

@wimrijnders You're right, I mistakenly thought there was a huge performance advantage. It's a shame though that they're not releasing the specs.

[lyogavin]

Seems like it's figured out here: https://github.com/Idein/py-videocore6.

Any plan to support Pi4?

[wimrijnders]

That's the very repo I'm investigating for VideoCore 6 functionality. I'm looking into it.

…

On 5/19/20, Gavin Li ***@***.***> wrote: Seems like it's figured out here: https://github.com/Idein/py-videocore6. Any plan to support Pi4? -- You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub: #75 (comment)

-- Met vriendelijke groet, Wim Rijnders http://axizo.nl

[lyogavin]

@wimrijnders you making any progress? you think this may work?

[lyogavin]

Maybe share some of your preliminary findings so that we can see if we can help?

[wimrijnders]

Nothing worth publishing, I'm afread.

The issue is that there is no documentation at all to be found about using VC6.
So, I downloaded the relevant driver code in the linux kernel (more specifically: the entire kernel and culling it), and I'm trying to get the relevant funtionality working from there.

The other thing I tried is looking at similar projects in other languages (notably python, the project link is above) and destill the relevant stuff from there. That went well up to a certain extent.

TBH it's an ordeal. If you know of a better approach, please tell.

[madtom1999]

On 09/07/2020 14:53, wimrijnders wrote: Nothing worth publishing, I'm afread. The issue is that there is no documentation at all to be found about using VC6. So, I downloaded the relevant driver code in the linux kernel (more specifically: the entire kernel and culling it), and I'm trying to get the relevant funtionality working from there. The other thing I tried is looking at similar projects in other languages (notably python) and destill the relevant stuff from there. That went well up to a certain extent. TBH it's an ordeal. If you know of a better approach, please tell. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#75 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABJUUC24JPNQMA6DRGG2RHLR2XDWJANCNFSM4JNKAYUQ>.

Would contacting the device drivers code authors be of help? Tom

[wimrijnders]

Not really. All they have to say about using vc4 and vc6 is in the code.

…

On Fri, Jul 10, 2020 at 5:30 PM madtom1999 ***@***.***> wrote: On 09/07/2020 14:53, wimrijnders wrote: > > Nothing worth publishing, I'm afread. > > The issue is that there is no documentation at all to be found about > using VC6. > So, I downloaded the relevant driver code in the linux kernel (more > specifically: the entire kernel and culling it), and I'm trying to get > the relevant funtionality working from there. > > The other thing I tried is looking at similar projects in other > languages (notably python) and destill the relevant stuff from there. > That went well up to a certain extent. > > TBH it's an ordeal. If you know of a better approach, please tell. > > — > You are receiving this because you are subscribed to this thread. > Reply to this email directly, view it on GitHub > <#75 (comment)>, or > unsubscribe > < https://github.com/notifications/unsubscribe-auth/ABJUUC24JPNQMA6DRGG2RHLR2XDWJANCNFSM4JNKAYUQ >. > Would contacting the device drivers code authors be of help? Tom — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#75 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAF3YDO2RH3R63TV344CTADR24XYJANCNFSM4JNKAYUQ> .

[geerlingguy]

Also noting that you can overclock the GPU cores to 750 MHz (using gpu_freq=750 in /boot/config.txt—also set over_voltage=6), which would bring about 48 Gflop/s, right?

[wimrijnders]

@geerlingguy Hey, interesting! So I add that line to config.txt and reboot, is it really that simple?

[geerlingguy]

@wimrijnders - Yes, though I would also recommend either a good heatsink or any kind of fan to move air over the SoC after the overclock, as it will make it a little warmer and could lead to throttling if it hits 85°C.

[doleron]

Hi @wimrijnders, sorry for ask again. But do you have any news about PI4 support? Thank you in advanced for all the great job on QPULib!

[wimrijnders]

@doleron Wow, your timing is perfect. I'm just lost for words.

I just launched today. Have a look at V3DLib, the spinoff of this project, with added VideoCore VI.

[doleron]

@wimrijnders there are no words to say how it is amazing! Looking forward to check it there! Cloning V3Dlib in 3... 2... 1...