From: Nicolas Boichat <drinkcat@chromium.org>
To: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Devicetree List <devicetree@vger.kernel.org>,
Tomeu Vizoso <tomeu.vizoso@collabora.com>,
David Airlie <airlied@linux.ie>,
lkml <linux-kernel@vger.kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>,
dri-devel@lists.freedesktop.org,
Steven Price <steven.price@arm.com>,
Rob Herring <robh+dt@kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
Hsin-Yi Wang <hsinyi@chromium.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 4/7] drm/panfrost: Add support for a second regulator for the GPU
Date: Thu, 9 Jan 2020 06:52:32 +0800 [thread overview]
Message-ID: <CANMq1KBo8ND+YDHaCw3yZZ0RUr69-NSUcVbqu38DuZvHUB-LFw@mail.gmail.com> (raw)
In-Reply-To: <20200108132302.GA3817@sirena.org.uk>
On Wed, Jan 8, 2020 at 9:23 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Wed, Jan 08, 2020 at 01:23:34PM +0800, Nicolas Boichat wrote:
>
> > Some GPUs, namely, the bifrost/g72 part on MT8183, have a second
> > regulator for their SRAM, let's add support for that.
>
> > + pfdev->regulator_sram = devm_regulator_get_optional(pfdev->dev, "sram");
> > + if (IS_ERR(pfdev->regulator_sram)) {
>
> This supply is required for the devices that need it so I'd therefore
> expect the driver to request the supply non-optionally based on the
> compatible string rather than just hoping that a missing regulator isn't
> important.
That'd be a bit awkward to match, though... Currently all bifrost
share the same compatible "arm,mali-bifrost", and it'd seem
weird/wrong to match "mediatek,mt8183-mali" in this driver? I have no
idea if any other Mali implementation will require a second regulator,
but with the MT8183 we do need it, see below.
> Though I do have to wonder given the lack of any active
> management of the supply if this is *really* part of the GPU or if it's
> more of a SoC thing, it's not clear what exactly adding this code is
> achieving.
Well if devfreq was working (see patch 7
https://patchwork.kernel.org/patch/11322851/ for a partial
implementation), it would adjust both mali and sram regulators, see
the OPP table in patch 2
(https://patchwork.kernel.org/patch/11322825/): SRAM voltage needs to
be increased for frequencies >=698Mhz.
Now if you have some better idea how to implement this, I'm all ears!
Thanks.
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next prev parent reply other threads:[~2020-01-08 22:52 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-08 5:23 [PATCH v2 0/7] Add dts for mt8183 GPU (and misc panfrost patches) Nicolas Boichat
2020-01-08 5:23 ` [PATCH v2 1/7] dt-bindings: gpu: mali-bifrost: Add Mediatek MT8183 Nicolas Boichat
2020-01-08 5:23 ` [PATCH v2 2/7] arm64: dts: mt8183: Add node for the Mali GPU Nicolas Boichat
2020-01-08 5:23 ` [PATCH v2 3/7] drm/panfrost: Improve error reporting in panfrost_gpu_power_on Nicolas Boichat
2020-01-09 12:03 ` Steven Price
2020-01-08 5:23 ` [PATCH v2 4/7] drm/panfrost: Add support for a second regulator for the GPU Nicolas Boichat
2020-01-08 13:23 ` Mark Brown
2020-01-08 22:52 ` Nicolas Boichat [this message]
2020-01-09 14:14 ` Steven Price
2020-01-09 16:28 ` Mark Brown
2020-01-09 16:53 ` Steven Price
2020-01-09 19:49 ` Mark Brown
2020-01-10 11:30 ` Steven Price
2020-01-14 7:21 ` Nicolas Boichat
2020-01-09 16:56 ` Rob Herring
2020-01-10 11:39 ` Steven Price
2020-01-08 5:23 ` [PATCH v2 5/7] drm/panfrost: Add support for multiple power domain support Nicolas Boichat
2020-01-09 14:08 ` Steven Price
2020-01-10 1:53 ` Nicolas Boichat
2020-01-27 7:55 ` Ulf Hansson
2020-02-07 2:04 ` Nicolas Boichat
2020-02-07 2:04 ` Nicolas Boichat
2020-01-08 5:23 ` [PATCH v2 6/7, RFC] drm/panfrost: Add bifrost compatible string Nicolas Boichat
2020-01-09 14:11 ` Steven Price
2020-01-08 5:23 ` [PATCH v2 7/7, RFC]: drm/panfrost: devfreq: Add support for 2 regulators Nicolas Boichat
2020-01-08 20:09 ` Rob Herring
2020-01-08 22:44 ` Nicolas Boichat
2020-01-08 12:56 ` [PATCH v2 0/7] Add dts for mt8183 GPU (and misc panfrost patches) Alyssa Rosenzweig
2020-01-09 9:08 ` Nicolas Boichat
2020-01-09 12:01 ` Steven Price
2020-01-09 13:10 ` Robin Murphy
2020-01-09 13:29 ` Steven Price
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