Etnaviv Driver Wires Up PPU Flop Reset Support Needed By Some Vivante Hardware
Sent out today was the latest batch of drm-misc-next changes to DRM-Next for staging ahead of the upcoming Linux 6.20~7.0 kernel cycle. The reverse-engineered Etnaviv DRM driver for Vivante graphics/NPU hardware has added a new "PPU flop reset" feature gleaned off studying the downstream vendor kernel driver.
Gert Wollny of Collabora has sorted out this PPU flop reset feature needed some Vivante hardware implementations. The PPU flop reset is used for clearing temporary registers of the GPU.
This functionality was sorted through by looking at the public "Galcore" kernel module for the downstream ST Microelectronics vendor kernel. The feature for now is required and used on Vivante SoC chip model 0x8000 and revision 0x6205. The code does add a new "force_flop_reset" kernel module parameter for the Etnaviv kernel driver for forcing the feature for other Vivante hardware for testing where this feature may be needed to clear temporary registers.
In addition to this PPU flop reset support for Etnaviv, this week's drm-misc-next also brings big endian fixes to the ASpeed AST driver, Panfrost supporting partial unmaps of huge pages, VM termination fixes for the Arm Panfrost drivers, and various other bug fixes. See this pull request for all the details.
Gert Wollny of Collabora has sorted out this PPU flop reset feature needed some Vivante hardware implementations. The PPU flop reset is used for clearing temporary registers of the GPU.
This functionality was sorted through by looking at the public "Galcore" kernel module for the downstream ST Microelectronics vendor kernel. The feature for now is required and used on Vivante SoC chip model 0x8000 and revision 0x6205. The code does add a new "force_flop_reset" kernel module parameter for the Etnaviv kernel driver for forcing the feature for other Vivante hardware for testing where this feature may be needed to clear temporary registers.
In addition to this PPU flop reset support for Etnaviv, this week's drm-misc-next also brings big endian fixes to the ASpeed AST driver, Panfrost supporting partial unmaps of huge pages, VM termination fixes for the Arm Panfrost drivers, and various other bug fixes. See this pull request for all the details.