linux-kernel - [PATCH v3 0/6] drm/panfrost: Turn off clocks and regulators in PM

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Message-ID: <20231109102543.42971-1-angelogioacchino.delregno@collabora.com>
Date:   Thu,  9 Nov 2023 11:25:37 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     boris.brezillon@...labora.com
Cc:     robh@...nel.org, steven.price@....com,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        wenst@...omium.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, kernel@...labora.com
Subject: [PATCH v3 0/6] drm/panfrost: Turn off clocks and regulators in PM

Changes in v3:
 - Fixed the order of set_opp/opp_put in patch [5/6]
 - Clearly specified MediaTek SoC models in patches [4/6], [6/6]
 - Reordered clk_disable() for suspend in patch [3/6]
 - Fixed blank line removal and alignment in patch [1/6]

Changes in v2:
 - Added hard reset GPU recovery
 - Tightened polling time for soft reset and power on
 - New execution time measurements after poweroff fix (see [1])

[1]: https://lore.kernel.org/all/20231102141507.73481-1-angelogioacchino.delregno@collabora.com/

At least MediaTek platforms are able to get the GPU clocks and regulators
completely off during system suspend, allowing to save a bit of power.

Panfrost is used on more than just MediaTek SoCs and the benefits of this
can be variable across different SoC models and/or different SoCs from
different manufacturers: this means that just adding this ability for all
could result in unexpected issues and breakages on untested SoCs.

For the aforemenetioned reasons, turning off the clocks and/or regulators
was implemented inside of a capabilities barrier that shall be enabled on
a per-SoC basis (in the panfrost_compatible platform data) after testing
of both benefits and feasibility.

In this series, I am adding the ability to switch on/off clocks and
regulators and enabling that on all MediaTek platforms, as I was able
to successfully test that on multiple Chromebooks featuring different
MediaTek SoCs; specifically, I've manually tested on MT8186, MT8192 and
MT8195, while MT8183 got tested only by KernelCI.

Cheers!

AngeloGioacchino Del Regno (6):
  drm/panfrost: Perform hard reset to recover GPU if soft reset fails
  drm/panfrost: Tighten polling for soft reset and power on
  drm/panfrost: Implement ability to turn on/off GPU clocks in suspend
  drm/panfrost: Set clocks on/off during system sleep on MediaTek SoCs
  drm/panfrost: Implement ability to turn on/off regulators in suspend
  drm/panfrost: Set regulators on/off during system sleep on MediaTek
    SoCs

 drivers/gpu/drm/panfrost/panfrost_device.c | 78 ++++++++++++++++++++--
 drivers/gpu/drm/panfrost/panfrost_device.h | 13 ++++
 drivers/gpu/drm/panfrost/panfrost_drv.c    |  3 +
 drivers/gpu/drm/panfrost/panfrost_gpu.c    | 21 ++++--
 drivers/gpu/drm/panfrost/panfrost_regs.h   |  1 +
 5 files changed, 105 insertions(+), 11 deletions(-)

-- 
2.42.0