- Mali 4xx GPUs have two kinds of processors GP and PP. GP is for
OpenGL vertex shader processing and PP is for fragment shader
processing. Each processor has its own MMU so prcessors work in
virtual address space.
- There's only one GP but multiple PP (max 4 for mali 400 and 8
for mali 450) in the same mali 4xx GPU. All PPs are grouped
togather to handle a single fragment shader task divided by
FB output tiled pixels. Mali 400 user space driver is
responsible for assign target tiled pixels to each PP, but mali
450 has a HW module called DLBU to dynamically balance each
PP's load.
- User space driver allocate buffer object and map into GPU
virtual address space, upload command stream and draw data with
CPU mmap of the buffer object, then submit task to GP/PP with
a register frame indicating where is the command stream and misc
settings.
- There's no command stream validation/relocation due to each user
process has its own GPU virtual address space. GP/PP's MMU switch
virtual address space before running two tasks from different
user process. Error or evil user space code just get MMU fault
or GP/PP error IRQ, then the HW/SW will be recovered.
- Use GEM+shmem for MM. Currently just alloc and pin memory when
gem object creation. GPU vm map of the buffer is also done in
the alloc stage in kernel space. We may delay the memory
allocation and real GPU vm map to command submission stage in the
furture as improvement.
- Use drm_sched for GPU task schedule. Each OpenGL context should
have a lima context object in the kernel to distinguish tasks
from different user. drm_sched gets task from each lima context
in a fair way.
mesa driver can be found here before upstreamed:
https://gitlab.freedesktop.org/lima/mesa
v8:
- add comments for in_sync
- fix ctx free miss mutex unlock
v7:
- remove lima_fence_ops with default value
- move fence slab create to device probe
- check pad ioctl args to be zero
- add comments for user/kernel interface
v6:
- fix comments by checkpatch.pl
v5:
- export gp/pp version to userspace
- rebase on drm-misc-next
v4:
- use get param interface to get info
- separate context create/free ioctl
- remove unused max sched task param
- update copyright time
- use xarray instead of idr
- stop using drmP.h
v3:
- fix comments from kbuild robot
- restrict supported arch to tested ones
v2:
- fix syscall argument check
- fix job finish fence leak since kernel 5.0
- use drm syncobj to replace native fence
- move buffer object GPU va map into kernel
- reserve syscall argument space for future info
- remove kernel gem modifier
- switch TTM back to GEM+shmem MM
- use time based io poll
- use whole register name
- adopt gem reservation obj integration
- use drm_timeout_abs_to_jiffies
Cc: Eric Anholt <eric@anholt.net>
Cc: Rob Herring <robh@kernel.org>
Cc: Christian König <ckoenig.leichtzumerken@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Andreas Baierl <ichgeh@imkreisrum.de>
Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Simon Shields <simon@lineageos.org>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Rob Herring <robh@kerrnel.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/291200/
Qiang Yu