From: Mark Brown <broonie@kernel.org>
To: "Martin Povišer" <povik+lin@cutebit.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Hector Martin <marcan@marcan.st>, Sven Peter <sven@svenpeter.dev>,
Philipp Zabel <p.zabel@pengutronix.de>,
Alyssa Rosenzweig <alyssa@rosenzweig.io>,
asahi@lists.linux.dev, alsa-devel@alsa-project.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/4] ASoC: apple: mca: Start new platform driver
Date: Tue, 23 Aug 2022 12:31:32 +0100 [thread overview]
Message-ID: <YwS6lHeGH0BZKHeB@sirena.org.uk> (raw)
In-Reply-To: <24C0ABFA-BF71-4492-8A6A-E9BE1462B403@cutebit.org>
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On Tue, Aug 23, 2022 at 09:33:36AM +0200, Martin Povišer wrote:
> > On 22. 8. 2022, at 19:39, Mark Brown <broonie@kernel.org> wrote:
> > On Fri, Aug 19, 2022 at 02:54:29PM +0200, Martin Povišer wrote:
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +/*
> >> + * Apple SoCs MCA driver
> >> + *
> >> + * Copyright (C) The Asahi Linux Contributors
> >> + *
> >> + * The MCA peripheral is made up of a number of identical units called clusters.
> > Please make the entire comment block a C++ one so things look more
> > intentional.
> Is this so that it does not look like the SPDX header was added
> mechanically? I will do it, just curious what the reasoning is.
Yes, broadly.
> >> + /*
> >> + * We can't power up the device earlier than this because
> >> + * the power state driver would error out on seeing the device
> >> + * as clock-gated.
> >> + */
> >> + cl->pd_link = device_link_add(mca->dev, cl->pd_dev,
> >> + DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME |
> >> + DL_FLAG_RPM_ACTIVE);
> > I'm not clear on this dynamically adding and removing device links stuff
> > - it looks like the main (only?) purpose is to take a runtime PM
> > reference to the target device which is fine but it's not clear why
> > device links are involved given that the links are created and destroyed
> > every time the DAI is used, AFAICT always in the same fixed
> > relationship. It's not a problem, it's just unclear.
> Indeed the only purpose is powering up the cluster’s power domain (there’s
> one domain for each cluster). Adding the links is the only way I know to
> do it. They need to be added dynamically (as opposed to statically linking,
> say, the DAI’s ->dev to the cluster’s ->pd_dev, which I guess may do
> something similar), because we need to sequence the power-up/power-down
> with the enablement of the clocks.
You could also just do the underlying runtime power management
operations directly couldn't you? It's not clear what the device link
stuff is adding.
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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: "Martin Povišer" <povik+lin@cutebit.org>
Cc: devicetree@vger.kernel.org, alsa-devel@alsa-project.org,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Sven Peter <sven@svenpeter.dev>, Hector Martin <marcan@marcan.st>,
Liam Girdwood <lgirdwood@gmail.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
asahi@lists.linux.dev, Philipp Zabel <p.zabel@pengutronix.de>,
Alyssa Rosenzweig <alyssa@rosenzweig.io>
Subject: Re: [PATCH v2 3/4] ASoC: apple: mca: Start new platform driver
Date: Tue, 23 Aug 2022 12:31:32 +0100 [thread overview]
Message-ID: <YwS6lHeGH0BZKHeB@sirena.org.uk> (raw)
In-Reply-To: <24C0ABFA-BF71-4492-8A6A-E9BE1462B403@cutebit.org>
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On Tue, Aug 23, 2022 at 09:33:36AM +0200, Martin Povišer wrote:
> > On 22. 8. 2022, at 19:39, Mark Brown <broonie@kernel.org> wrote:
> > On Fri, Aug 19, 2022 at 02:54:29PM +0200, Martin Povišer wrote:
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +/*
> >> + * Apple SoCs MCA driver
> >> + *
> >> + * Copyright (C) The Asahi Linux Contributors
> >> + *
> >> + * The MCA peripheral is made up of a number of identical units called clusters.
> > Please make the entire comment block a C++ one so things look more
> > intentional.
> Is this so that it does not look like the SPDX header was added
> mechanically? I will do it, just curious what the reasoning is.
Yes, broadly.
> >> + /*
> >> + * We can't power up the device earlier than this because
> >> + * the power state driver would error out on seeing the device
> >> + * as clock-gated.
> >> + */
> >> + cl->pd_link = device_link_add(mca->dev, cl->pd_dev,
> >> + DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME |
> >> + DL_FLAG_RPM_ACTIVE);
> > I'm not clear on this dynamically adding and removing device links stuff
> > - it looks like the main (only?) purpose is to take a runtime PM
> > reference to the target device which is fine but it's not clear why
> > device links are involved given that the links are created and destroyed
> > every time the DAI is used, AFAICT always in the same fixed
> > relationship. It's not a problem, it's just unclear.
> Indeed the only purpose is powering up the cluster’s power domain (there’s
> one domain for each cluster). Adding the links is the only way I know to
> do it. They need to be added dynamically (as opposed to statically linking,
> say, the DAI’s ->dev to the cluster’s ->pd_dev, which I guess may do
> something similar), because we need to sequence the power-up/power-down
> with the enablement of the clocks.
You could also just do the underlying runtime power management
operations directly couldn't you? It's not clear what the device link
stuff is adding.
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next prev parent reply other threads:[~2022-08-23 15:40 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 12:54 [PATCH v2 0/4] ASoC platform driver for Apple MCA Martin Povišer
2022-08-19 12:54 ` Martin Povišer
2022-08-19 12:54 ` [PATCH v2 1/4] dt-bindings: sound: Add Apple MCA I2S transceiver Martin Povišer
2022-08-19 12:54 ` Martin Povišer
2022-08-19 12:58 ` Martin Povišer
2022-08-19 12:58 ` Martin Povišer
2022-08-19 13:08 ` Krzysztof Kozlowski
2022-08-19 13:08 ` Krzysztof Kozlowski
2022-08-19 13:09 ` Krzysztof Kozlowski
2022-08-19 13:09 ` Krzysztof Kozlowski
2022-08-19 14:14 ` Martin Povišer
2022-08-19 14:14 ` Martin Povišer
2022-08-19 14:17 ` Krzysztof Kozlowski
2022-08-19 14:17 ` Krzysztof Kozlowski
2022-08-22 18:59 ` Rob Herring
2022-08-22 18:59 ` Rob Herring
2022-08-19 12:54 ` [PATCH v2 2/4] arm64: dts: apple: t8103: Add MCA and its support Martin Povišer
2022-08-19 12:54 ` Martin Povišer
2022-08-19 13:12 ` Krzysztof Kozlowski
2022-08-19 13:12 ` Krzysztof Kozlowski
2022-08-19 14:24 ` Martin Povišer
2022-08-19 14:24 ` Martin Povišer
2022-08-23 11:02 ` Krzysztof Kozlowski
2022-08-23 11:02 ` Krzysztof Kozlowski
2022-08-19 12:54 ` [PATCH v2 3/4] ASoC: apple: mca: Start new platform driver Martin Povišer
2022-08-19 12:54 ` Martin Povišer
2022-08-22 17:39 ` Mark Brown
2022-08-22 17:39 ` Mark Brown
2022-08-23 7:33 ` Martin Povišer
2022-08-23 7:33 ` Martin Povišer
2022-08-23 11:31 ` Mark Brown [this message]
2022-08-23 11:31 ` Mark Brown
2022-08-23 11:51 ` Martin Povišer
2022-08-23 11:51 ` Martin Povišer
2022-08-23 11:53 ` Martin Povišer
2022-08-23 11:53 ` Martin Povišer
2022-08-19 12:54 ` [PATCH v2 4/4] ASoC: apple: mca: Add locks on foreign cluster access Martin Povišer
2022-08-19 12:54 ` Martin Povišer
2022-08-22 17:45 ` Mark Brown
2022-08-22 17:45 ` Mark Brown
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