Hi Josef, Am Freitag, dem 01.08.2025 um 13:06 +0200 schrieb Josef Luštický: > Hello, > I am trying to get GPU acceleration to work with SPI display using > ili9225_dri.so, > and I use kmscube to test. > The SoC is STM32MP157c with Vivante GC400 GPU and I use Mesa3D 24.0.9 > (rootfs generated with Buildroot 2025.02.3) and kernel 5.10.176 (from > STM). > > I also have the same system with MIPI Display attached. > While kmscube renders at 60 fps with the MIPI Display system, I get > only 11 fps with the SPI display. Apart from that both systems are the > same.
The question is what can you expect from a SPI display? SPI is not a great interface for isochronous traffic with quite high bandwidth demands. Even at really low resolutions you need a lot of bandwidth to update a display. What is the resolution and color depth of you display? How fast is your SPI connection? You might run modetest -v to get a reference point on how fast the display can be updated without any GPU rendering going on. Regards, Lucas > > I checked the output of kmscube and it prints the exact same extensions on > both, > the only difference is the framerate. > I also checked output of kmscube's /proc/PID/maps and the only > difference is that with MIPI Display it loads /usr/lib/dri/stm_dri.so > while with the SPI Display it loads /usr/lib/dri/ili9225_dri.so, > but I see those files are the same (hardlinks). > Both open /dev/dri/renderD128 (GPU). > > Why am I getting just 11 fps on the system with SPI Display? > Is there some architectural limitation, either in Mesa, kernel, or HW-related? > I suppose both setups use kernel's KMS as renderer only (kmsro), thus > it should render at the same framerate. > The difference in HW is the peripheral the displays use - LTDC > (stm_dri.so) vs. SPI (eventually ili9225_dri.so). > Why do I see no /usr/lib/etnaviv_dri.so loaded? > > The MIPI Display is attached to the LTDC (LCD Timing Display > Controller) peripheral of the STM SoC and the display driver is > drivers/gpu/drm/panel/panel-sitronix-st7703.c (DRM panel). > > The SPI display driver uses the kernel's TinyDRM API and its driver is > drivers/gpu/drm/tiny/ili9225.c. > > I also tried softpipe (disabled GPU in device-tree) and it renders 7 > fps on both systems. > > I attach the output from kmscube on the SPI Display system (the MIPI > Display is the same except framerate is 60 fps.) > > Kind regards > Josef Lusticky
