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From:   Nicolas Boichat <drinkcat@chromium.org>
Date:   Thu, 9 Jan 2020 17:08:46 +0800
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Subject: Re: [PATCH v2 0/7] Add dts for mt8183 GPU (and misc panfrost patches)
To:     Rob Herring <robh+dt@kernel.org>
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        Mark Rutland <mark.rutland@arm.com>,
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On Wed, Jan 8, 2020 at 1:23 PM Nicolas Boichat <drinkcat@chromium.org> wrote:
>
> Hi!
>
> Sorry for the long delay since https://patchwork.kernel.org/patch/11132381/,
> finally got around to give this a real try.
>
> The main purpose of this series is to upstream the dts change and the binding
> document, but I wanted to see how far I could probe the GPU, to check that the
> binding is indeed correct. The rest of the patches are RFC/work-in-progress, but
> I think some of them could already be picked up.
>
> So this is tested on MT8183 with a chromeos-4.19 kernel, and a ton of
> backports to get the latest panfrost driver (I should probably try on
> linux-next at some point but this was the path of least resistance).
>
> I tested it as a module as it's more challenging (originally probing would
> work built-in, on boot, but not as a module, as I didn't have the power
> domain changes, and all power domains are on by default during boot).
>
> Probing logs looks like this, currently:
> [  221.867726] panfrost 13040000.gpu: clock rate = 511999970
> [  221.867929] panfrost 13040000.gpu: Linked as a consumer to regulator.14
> [  221.868600] panfrost 13040000.gpu: Linked as a consumer to regulator.31
> [  221.870586] panfrost 13040000.gpu: Linked as a consumer to genpd:0:13040000.gpu
> [  221.871492] panfrost 13040000.gpu: Linked as a consumer to genpd:1:13040000.gpu
> [  221.871866] panfrost 13040000.gpu: Linked as a consumer to genpd:2:13040000.gpu
> [  221.872427] panfrost 13040000.gpu: mali-g72 id 0x6221 major 0x0 minor 0x3 status 0x0
> [  221.872439] panfrost 13040000.gpu: features: 00000000,13de77ff, issues: 00000000,00000400
> [  221.872445] panfrost 13040000.gpu: Features: L2:0x07120206 Shader:0x00000000 Tiler:0x00000809 Mem:0x1 MMU:0x00002830 AS:0xff JS:0x7
> [  221.872449] panfrost 13040000.gpu: shader_present=0x7 l2_present=0x1
> [  221.873526] panfrost 13040000.gpu: error powering up gpu stack
> [  221.878088] [drm] Initialized panfrost 1.1.0 20180908 for 13040000.gpu on minor 2
> [  221.940817] panfrost 13040000.gpu: error powering up gpu stack
> [  222.018233] panfrost 13040000.gpu: error powering up gpu stack
> (repeated)
>
> So the GPU is probed, but there's an issue when powering up the STACK, not
> quite sure why, I'll try to have a deeper look, at some point.

Just as a follow-up to that one. stack_present=0x00000007 on my GPU.

However, the ARM-provided driver I use on this platform doesn't have
CONFIG_MALI_CORESTACK enabled so the "stack" is never turned on.
https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.19/drivers/gpu/arm/midgard/Kconfig#101
. So possibly this does not need to be done on Bifrost GPUs (and the
error should be harmless).

> Thanks!
>
> Nicolas
>
> v2:
>  - Use sram instead of mali_sram as SRAM supply name.
>  - Rename mali@ to gpu@.
>  - Add dt-bindings changes
>  - Stacking patches after the device tree change that allow basic
>    probing (still incomplete and broken).
>
> Nicolas Boichat (7):
>   dt-bindings: gpu: mali-bifrost: Add Mediatek MT8183
>   arm64: dts: mt8183: Add node for the Mali GPU
>   drm/panfrost: Improve error reporting in panfrost_gpu_power_on
>   drm/panfrost: Add support for a second regulator for the GPU
>   drm/panfrost: Add support for multiple power domain support
>   RFC: drm/panfrost: Add bifrost compatible string
>   RFC: drm/panfrost: devfreq: Add support for 2 regulators
>
>  .../bindings/gpu/arm,mali-bifrost.yaml        |  20 ++++
>  arch/arm64/boot/dts/mediatek/mt8183-evb.dts   |   7 ++
>  arch/arm64/boot/dts/mediatek/mt8183.dtsi      | 104 +++++++++++++++++
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c   |  18 +++
>  drivers/gpu/drm/panfrost/panfrost_device.c    | 108 ++++++++++++++++--
>  drivers/gpu/drm/panfrost/panfrost_device.h    |   7 ++
>  drivers/gpu/drm/panfrost/panfrost_drv.c       |   1 +
>  drivers/gpu/drm/panfrost/panfrost_gpu.c       |  15 ++-
>  8 files changed, 267 insertions(+), 13 deletions(-)
>
> --
> 2.24.1.735.g03f4e72817-goog
>