Hello,
I'm working on a product that originally had kernel linux-imx kernel 4.1.15 (imx_4.1.15_2.0.0_ga) that utilised vivante GPU driver with 1280x800px screen with Kanzi and directfb. Performance was good and no artefacts were seen on product display.
Since the product required kernel upgrade for various different reasons the new kernel of choice became linux-fslc kernel 4.20 (4.20.x+fslc), that utilises etnaviv GPU driver and DRM.
After upgrade the GPU performance is not good any longer. A deeper dive in the strace and ltrace indicates calls to MESA taking at least twice the time that we had with kernel 4.1.15. Some operations take even longer time such as eglSwapBuffers (approx 8 times longer time than in 4.1.15).
Questions:
1) Does anyone have a working etnaviv configuration to share that has both 2D and 3D acceleration enabled at good performance level to post in this ticket here so I can compare?
2) Is it realistic that drawing artefacts can appear (i.e. large white spots or pixels of incorrect color) on screen purely if CPU is overloaded or is this more sign of buggy GPU driver
3) Reading etnaviv sources - is MMU absolutely needed for etnaviv driver to function correctly?
4) Asking for recommendation - do you know crucial mistakes in 4.20 kernel etnaviv GPU implementation? Are there any strong reasons to backport etnaviv driver from more recent kernel to 4.20?
5) Is there a specific MESA library revision that you know that works well together with kernel 4.20
Thank you in advance in this investigation...
