[PATCH v4 0/2] drm: lima: devfreq and cooling device support

From: Martin Blumenstingl
Date: Thu Mar 19 2020 - 16:35:05 EST


This is my attempt at adding devfreq (and cooling device) support to
the lima driver.

Test results from a Meson8m2 board:
TEST #1: glmark2-es2-drm --off-screen in an infinite loop while cycling
through all available frequencies using the userspace governor

From : To
: 182142857 318750000 425000000 510000000 637500000 time(ms)
182142857: 0 1274 1274 1273 1279 5399468
318750000: 1274 0 1274 1273 1272 5114700
425000000: 1276 1274 0 1272 1271 5122008
510000000: 1909 1273 1273 0 636 5274292
* 637500000: 640 1272 1272 1273 0 5186796
Total transition : 24834

TEST #2: glmark2-es2-drm --off-screen in an infinite loop with the
simple_ondemand governor
From : To
: 182142857 318750000 425000000 510000000 637500000 time(ms)
182142857: 0 0 0 0 203 318328
318750000: 53 0 0 0 21 56044
425000000: 27 18 0 0 2 34172
510000000: 27 6 14 0 1 41348
* 637500000: 95 50 33 48 0 2085312


Changes since RFC v3 at [2]:
- fix devfreq init error handling and allow lima_devfreq_fini to be
called multiple times (thanks Qiang)
- switch from atomic counter to a simple int which is only accessed
under the devfreq spinlock (thanks Qiang)
- union lock areas in same function (thanks Qiang)
- select DEVFREQ_GOV_SIMPLE_ONDEMAND like panfrost does (thanks Qiang)
- move lima_devfreq struct to lima_devfreq.h (thanks Qiang)
- fix duplicate variable in lima_sched_pipe_task_done
- only call dev_pm_opp_of_remove_table if dev_pm_opp_of_add_table
succeeded previously
- update copyright year to 2020
- rebased on top of drm-misc-next
- dropped RFC status

Changes since RFC v2 at [1]:
- added #cooling-cells to the dt-bindings (new patch #1)
- skip devfreq initialization when the operating-points-v2 property is
absent
- call dev_pm_opp_set_regulators() so devfreq will actually manage the
mali-supply regulator
- rebased on top of drm-misc-next-2020-02-21

Changes since RFC v1 at [0]:
- added lock to protect the statistics as these can be written
concurrently for example when the GP and PP IRQ are firing at the
same time. Thanks to Qiang Yu for the suggestion!
- updated the copyright notice of lima_devfreq.c to indicate that the
code is derived from panfrost_devfreq.c. Thanks to Chen-Yu Tsai for
the suggestion!
- I did not unify the code with panfrost yet because I don't know where
to put the result. any suggestion is welcome though!


[0] https://patchwork.freedesktop.org/series/70967/
[1] https://patchwork.kernel.org/cover/11311293/
[2] https://patchwork.kernel.org/cover/11398365/


Martin Blumenstingl (2):
dt-bindings: gpu: mali-utgard: Add the #cooling-cells property
drm/lima: Add optional devfreq and cooling device support

.../bindings/gpu/arm,mali-utgard.yaml | 4 +
drivers/gpu/drm/lima/Kconfig | 2 +
drivers/gpu/drm/lima/Makefile | 3 +-
drivers/gpu/drm/lima/lima_devfreq.c | 234 ++++++++++++++++++
drivers/gpu/drm/lima/lima_devfreq.h | 41 +++
drivers/gpu/drm/lima/lima_device.c | 4 +
drivers/gpu/drm/lima/lima_device.h | 3 +
drivers/gpu/drm/lima/lima_drv.c | 14 +-
drivers/gpu/drm/lima/lima_sched.c | 7 +
drivers/gpu/drm/lima/lima_sched.h | 3 +
10 files changed, 312 insertions(+), 3 deletions(-)
create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h

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2.25.2