[PATCH v3 0/4] Power Management for Raspberry Pi V3D GPU

[Maíra Canal]

This series introduces Runtime Power Management (PM) support for the
Raspberry Pi V3D GPU.

Currently, the V3D clock remains enabled for the entire system uptime,
even when the GPU is idle. With the introduction of Runtime PM, the
clock can now be disabled during idle periods. For example, with this
series applied on a Raspberry Pi 5, if we check `vcgencmd measure_clock
v3d`, we get:

(idle)

$ vcgencmd measure_clock v3d
frequency(0)=0

(running glmark2)

$ vcgencmd measure_clock v3d
frequency(0)=960016128

One particular change was required in this version to ensure a
meaningful reduction in idle power consumption: the V3D clock rate must
be explicitly set to the minimum rate during suspend. As explained in
an inline comment, this is needed as some firmware versions may not
fully power off the clock when its state is set to off. This issue can
be mitigated by setting the clock rate to 0 during suspend. For this
same reason, PATCH 1/4 has been added in this version.

Apart from that, the v3d patches are mostly identical to v2, but rebased
on top of drm-misc-next.

To ease testing in Raspberry Pi 4 and 5, I prepared a downstream branch
backporting this series to rpi-6.18.y [1].

[1] https://github.com/mairacanal/linux-rpi/tree/v3d/downstream/power-management-6.18

Best regards,
- Maíra

---
v1 -> v2: https://lore.kernel.org/r/20250728-v3d-power-management-v1-0-780f922b1048@igalia.com

- [1/5] NEW PATCH: "clk: bcm: rpi: Add missing logs if firmware fails" (Stefan Wahren)
- [2/5] Remove the "Fixes:" tag (Stefan Wahren)
- [2/5] dev_err_ratelimited() instead of dev_err() (Stefan Wahren)
- [2/5] Instead of logging the clock ID, use clk_hw_get_name(hw) to log the name (Stefan Wahren)
- [2/5] Add a newline character at the end of the log message (Stefan Wahren)
- [2/5] Use CLK_IS_CRITICAL for all clocks that can't be disabled (Maxime Ripard)
- [3/5] NEW PATCH: "clk: bcm: rpi: Maximize V3D clock"
- [4/5] Use devm_reset_control_get_optional_exclusive() (Philipp Zabel)
- [4/5] Make sure that resource are cleaned in the inverse order of allocation (Philipp Zabel)

v2 -> v3: https://lore.kernel.org/r/20250731-v3d-power-management-v2-0-032d56b01964@igalia.com

- Rebased on top of drm-misc-next
- Patches "[PATCH v2 1/5] clk: bcm: rpi: Add missing logs if firmware
  fails", "[PATCH v2 2/5] clk: bcm: rpi: Turn firmware clock on/off when
  preparing/unpreparing", and "[PATCH v2 3/5] clk: bcm: rpi: Maximize
  V3D clock" were applied to clk-next.
- [1/4] NEW PATCH: "clk: bcm: rpi: Let V3D consumers manage clock rate"
- [2/4] NEW PATCH: "clk: bcm: rpi: Mark PIXEL_CLK and HEVC_CLK as CLK_IGNORE_UNUSED"
- [3/4] Added Philipp's R-b (Philipp Zabel)
- [4/4] s/drm_err/DRM_ERROR
- [4/4] Set the clock rate to 0 during suspend and to the maximum rate
  during resume

---
Maíra Canal (4):
      clk: bcm: rpi: Let V3D consumers manage clock rate
      clk: bcm: rpi: Mark PIXEL_CLK and HEVC_CLK as CLK_IGNORE_UNUSED
      drm/v3d: Allocate all resources before enabling the clock
      drm/v3d: Introduce Runtime Power Management

 drivers/clk/bcm/clk-raspberrypi.c |   9 +--
 drivers/gpu/drm/v3d/Makefile      |   3 +-
 drivers/gpu/drm/v3d/v3d_debugfs.c |  23 +++++-
 drivers/gpu/drm/v3d/v3d_drv.c     | 163 ++++++++++++++++++--------------------
 drivers/gpu/drm/v3d/v3d_drv.h     |  23 +++++-
 drivers/gpu/drm/v3d/v3d_gem.c     |  21 ++++-
 drivers/gpu/drm/v3d/v3d_irq.c     |  15 ++--
 drivers/gpu/drm/v3d/v3d_mmu.c     |  12 ++-
 drivers/gpu/drm/v3d/v3d_power.c   |  96 ++++++++++++++++++++++
 drivers/gpu/drm/v3d/v3d_submit.c  |  19 ++++-
 10 files changed, 270 insertions(+), 114 deletions(-)
---
base-commit: 26b4309a3ab82a0697751cde52eb336c29c19035
change-id: 20250728-v3d-power-management-eebb2024dc96