In a perfect world we would be able to read GPU registers of interest via the command stream with a 'read-register' command/package. For perf counters it is a must to read them synchronized with the GPU to put the values in relation to a draw command. As Vivante GPUs do not provide this functionality we need to emulate it in software.
We need to support three different kind of perf register types:
1) normal register This is the easierst case where we can simply read the register and we are done.
2) debug register We need to configure the mux register and then read the debug register value.
3) pipeline register We need to 'iterate' over all pixel pipes and sum up the values. The 'iteration' is done by select the pipe of interest via HI_CLOCK_CONTROL_DEBUG_PIXEL_PIPE. There is also need to configure the mux register.
Allowing the userspace to do it all by its own feels quite error prone and not future-proof. Thats why the kernel exports all performance domains and their signals to the userspace via two new ioctls. So the kernel knows all performance counters and how to sample them.
At the moment all performacne domains and signals get exported to all gpu pipe types, but that can be changed in follow-up patches.
struct drm_etnaviv_gem_submit was extended to include so-called performance monitor requests (pmrs). A request defines what domain and signal should be sampled (pre/post draw cmdbuffer) and where to store the result.
The whole series can be found here: https://github.com/austriancoder/linux/tree/perfmon
Happy reviewing!
Christian Gmeiner (21): drm/etnaviv: add infrastructure to query perf counter drm/etnaviv: add uapi for perfmon feature drm/etnaviv: add internal representation of perfmon_request drm/etnaviv: extend etnaviv_gpu_cmdbuf_new(..) with nr_pmrs drm/etnaviv: add performance monitor request validation drm/etnaviv: copy pmrs from userspace drm/etnaviv: add performance monitor request processing drm/etnaviv: add 'sync point' support drm/etnaviv: clear alloced event drm/etnaviv: use 'sync points' for performance monitor requests drm/etnaviv: add HI perf domain drm/etnaviv: add PE perf domain drm/etnaviv: add SH perf domain drm/etnaviv: add PA perf domain drm/etnaviv: add SE perf domain drm/etnaviv: add RA perf domain drm/etnaviv: add TX perf domain drm/etnaviv: add MC perf domain drm/etnaviv: need to disable clock gating when doing profiling drm/etnaviv: enable debug registers on demand drm/etnaviv: submit supports performance monitor requests
drivers/gpu/drm/etnaviv/Makefile | 3 +- drivers/gpu/drm/etnaviv/etnaviv_buffer.c | 36 +++ drivers/gpu/drm/etnaviv/etnaviv_cmdbuf.c | 13 +- drivers/gpu/drm/etnaviv/etnaviv_cmdbuf.h | 6 +- drivers/gpu/drm/etnaviv/etnaviv_drv.c | 39 ++- drivers/gpu/drm/etnaviv/etnaviv_drv.h | 1 + drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 68 +++- drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 151 ++++++++- drivers/gpu/drm/etnaviv/etnaviv_gpu.h | 6 + drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 447 +++++++++++++++++++++++++++ drivers/gpu/drm/etnaviv/etnaviv_perfmon.h | 48 +++ include/uapi/drm/etnaviv_drm.h | 40 ++- 12 files changed, 836 insertions(+), 22 deletions(-) create mode 100644 drivers/gpu/drm/etnaviv/etnaviv_perfmon.c create mode 100644 drivers/gpu/drm/etnaviv/etnaviv_perfmon.h