[PATCH 0/3] drm/panfrost: Enable the GPU timestamp counter on MT8188

["Michał Kopeć" <michal@nozomi.space>]

On MT8188 the GPU timestamp counter reads zero until a register in the
MFG configuration block routes the SoC system timer to it, and the
setting is lost whenever the GPU power domain is turned off. As a
result, the SYSTEM_TIMESTAMP query and the timestamps written by jobs
are always zero, which breaks timestamp queries in userspace drivers.

This series adds an optional mediatek,mfgcfg phandle to the Mali
binding, uses it in panfrost to set the register on every power-up,
and adds it to the MT8188 GPU node. Without the phandle the driver
behaves as before.

MT8370 shares the GPU node and the MFG block with MT8188, so the
binding allows the phandle there too, but the driver only enables the
quirk on MT8188, where it was tested.

Patch 3 is meant for the MediaTek tree; patches 1 and 2 can go through
drm-misc.

Tested on the Lenovo Chromebook Duet Gen 9 (Ciri, MT8188): the 13 MHz
counter advances by 100 ms over a 100 ms sleep, also after resuming
from deep suspend.

Michał Kopeć (3):
  dt-bindings: gpu: mali-bifrost: Add the MT8188 MFGCFG phandle
  drm/panfrost: Enable the GPU timestamp counter on MT8188
  arm64: dts: mediatek: mt8188: Add the MFGCFG phandle to the GPU

 .../bindings/gpu/arm,mali-bifrost.yaml        | 17 ++++++++
 arch/arm64/boot/dts/mediatek/mt8188.dtsi      |  1 +
 drivers/gpu/drm/panfrost/panfrost_device.h    |  1 +
 drivers/gpu/drm/panfrost/panfrost_drv.c       |  1 +
 drivers/gpu/drm/panfrost/panfrost_gpu.c       | 39 +++++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_gpu.h       |  1 +
 6 files changed, 60 insertions(+)


base-commit: 70456f05d4b6396b22048c4b8cd3cb98ecf9f9e3
-- 
2.55.0