Test IT8951 displays

[joukos]

Comment on this issue for your experiences with the IT8951 support.

Tested:

• 6" - works
• 6" HD - works
• 7.8" - works
• 9.7" - works
• 10.3" - works

[math85360]

Tested with PaperTTY & VNC on Waveshare 9.7" with IT8951 :

Video Waveshare 9.7" eink displaying Midori browser with PaperTTY

[joukos]

Wow, that's beautiful, thanks!

[joukos]

@math85360, is it okay to add the image (and link to the video) to the README?

[math85360]

Yes, of course !

[markbirss]

Very nice, hope the 7.8 inch works well also

[jmi2k]

I'm getting a 7.8 inch screen soon, I'll report back if everything works fine. It should arrive in about a month.

[joukos]

@jmi2k cool, thanks :) Good luck!

[jeLee6gi]

Here is a terminal on the 7.8 using a raspberry pi 4 running archlinuxarm.

The CPU usage goes up to 100% periodically and even partial refreshes only happen every two seconds or so. Is that to be expected? The only thing I changed was the VCOM to match my display (-1.38V).

[jmi2k]

Right now the only SD card I have is 2GB so I'll have to wait until next week.

[joukos]

Thanks for letting us know @jeLee6gi !

The CPU usage goes up to 100% periodically and even partial refreshes only happen every two seconds or so. Is that to be expected?

Well, I haven't actually tried PaperTTY on a Pi4 and it's very likely there's room for optimization to at least make better use of the multiple cores. Do you use it in TTY or VNC mode? I don't think it should take very long to process an updated frame, but with a display that big, simply sending the data to it might take a while. With partial refresh there shouldn't be too much data to send though...

[chi-lambda]

I've done some profiling, because I use a Pi Zero (with a 6" display) and the problem is even more pronounced there. I only use TTY mode. It seems pack_image in driver_it8951.py is rather slow. I've done some optimization, but still need to test. I'll share it when I'm confident that it still works.

[joukos]

@chi-lambda thanks, performance improvement is always nice, hope it works. I wish we had some unit tests though so it would be easier to avoid anything breaking... ;)

[jeLee6gi]

Well, I haven't actually tried PaperTTY on a Pi4 and it's very likely there's room for optimization to at least make better use of the multiple cores. Do you use it in TTY or VNC mode? I don't think it should take very long to process an updated frame, but with a display that big, simply sending the data to it might take a while. With partial refresh there shouldn't be too much data to send though...

I only used TTY mode so far

I've done some profiling, because I use a Pi Zero (with a 6" display) and the problem is even more pronounced there. I only use TTY mode. It seems pack_image in driver_it8951.py is rather slow.

I also tried to profile:

import time

for i in range(1_000_000):
    print(i)
    time.sleep(1)

I ran this program run until it started scrolling the terminal and then profiled with py-spy for two minutes. Whenever spi_write was running, py-spy had trouble getting samples so it realistically it spent even more time in spi_write than it recorded. Anyways, this is how it spends its time and when it's scrolling like this I get a new image roughly every 8 to 15 seconds.