linux-kernel - Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

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Date:   Mon, 16 Dec 2019 10:51:32 +0800
From:   Qiang Yu <yuq825@...il.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        lima@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Rob Herring <robh@...nel.org>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        linux-rockchip@...ts.infradead.org, Chen-Yu Tsai <wens@...e.org>
Subject: Re: [RFC v1 0/1] drm: lima: devfreq and cooling device support

Thanks for adding this.

As the license, it's up to you, I think it's OK for now.

For the code, I think you may need some lock to protect the time records as
there are two kernel threads gp/pp will try to mark GPU busy and several
interrupts try to mark GPU idle.

Regards,
Qiang


On Mon, Dec 16, 2019 at 5:12 AM Martin Blumenstingl
<martin.blumenstingl@...glemail.com> wrote:
>
> This is my attempt at adding devfreq (and cooling device) support to
> the lima driver.
> I didn't have much time to do in-depth testing. However, I'm sending
> this out early because there are many SoCs with Mali-400/450 GPU so
> I want to avoid duplicating the work with somebody else.
>
> The code is derived from panfrost_devfreq.c which is why I kept the
> Collabora copyright in lima_devfreq.c. Please let me know if I should
> drop this or how I can make it more clear that I "borrowed" the code
> from panfrost.
>
> I am seeking comments in two general areas:
> - regarding the integration into the existing lima code
> - for the actual devfreq code (I had to adapt the panfrost code
>   slightly, because lima uses a bus and a GPU/core clock)
>
> My own TODO list includes "more" testing on various Amlogic SoCs.
> So far I have tested this on Meson8b and Meson8m2 (which both have a
> GPU OPP table defined). However, I still need to test this on a GXL
> board (which is currently missing the GPU OPP table).
>
>
> Martin Blumenstingl (1):
>   drm/lima: Add optional devfreq support
>
>  drivers/gpu/drm/lima/Kconfig        |   1 +
>  drivers/gpu/drm/lima/Makefile       |   3 +-
>  drivers/gpu/drm/lima/lima_devfreq.c | 162 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/lima/lima_devfreq.h |  15 +++
>  drivers/gpu/drm/lima/lima_device.c  |   4 +
>  drivers/gpu/drm/lima/lima_device.h  |  11 ++
>  drivers/gpu/drm/lima/lima_drv.c     |  14 ++-
>  drivers/gpu/drm/lima/lima_sched.c   |   7 ++
>  drivers/gpu/drm/lima/lima_sched.h   |   3 +
>  9 files changed, 217 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.c
>  create mode 100644 drivers/gpu/drm/lima/lima_devfreq.h
>
> --
> 2.24.1
>