Rotating display


#1

weird issue, if I use $ xrandr -o left the performance drops considerably to the point you can see each frame in glx-gears.

anyone has a better method?


#2

If you need permanent rotation, you can use a device tree setting. See this topic: Rotate Android Screen 180 & 280 degrees


#3

that’s for dsi, i need it on hdmi, also needs to work with mesa


#4

that’s for dsi, i need it on hdmi, also needs to work with mesa

freedreno allows full OpenGL programs to run even though the hardware is
designed for GLES only. This allows full desktop apps (like GNOME Shell)
to run well but is partly an illusion; I’m not an expert on this but
my internal mental model is that some operations that would normally be
done in “real” hardware on full GL hardware end up running on the
programmable parts of the GPU.

This causes some odd performance hazards… and if mesa has ended up
responsible for the screen rotate I suspect you might be hitting one.


#5

I talked to Rob Clark on this one and did some more tests:

  1. Its still running on the gpu
  2. Its limited by memory clock and bandwidth, as more bandwidth is required for rotated display, hence the slowdown in performance making it look like software rendering
  3. there is a hack patch available, i’ll need to check with the landing team if it has merged yet.