linux-kernel - Re: [RFC PATCH v2 3/5] ASoC: apple: Add MCA platform driver for Apple SoCs

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Date:   Mon, 6 Jun 2022 21:17:39 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Martin Povišer <povik+lin@...ebit.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mark Kettenis <kettenis@...nbsd.org>,
        Hector Martin <marcan@...can.st>,
        Sven Peter <sven@...npeter.dev>, asahi@...ts.linux.dev
Subject: Re: [RFC PATCH v2 3/5] ASoC: apple: Add MCA platform driver for
 Apple SoCs

On Mon, Jun 06, 2022 at 09:19:08PM +0200, Martin Povišer wrote:

> +++ b/sound/soc/apple/mca.c
> @@ -0,0 +1,1122 @@
> +/*
> + * Apple SoCs MCA driver

Please add SPDX headers to all your files.

> +		mca_modify(cl, serdes_conf,
> +			SERDES_CONF_SOME_RST, SERDES_CONF_SOME_RST);
> +		(void) readl_relaxed(cl->base + serdes_conf);

Please drop the cast, casts to/from void are generally a warning sign as
they're unneeded in C.  If you want to document the barrier use a
comment or wrapper function.

> +	/*
> +	 * Codecs require clocks at time of umute with the 'mute_stream' op.
> +	 * We need to enable them here at the latest (frontend prepare would
> +	 * be too late).
> +	 */
> +	if (!mca_fe_clocks_in_use(fe_cl)) {
> +		ret = mca_fe_enable_clocks(fe_cl);
> +		if (ret < 0)
> +			return ret;
> +	}

This requirement is CODEC specific.  It's fine to bodge around to
satisfy it though, especially given the restricted set of platforms this
can be used with.

> +	fe_cl = &mca->clusters[cl->port_driver];
> +	if (!mca_fe_clocks_in_use(fe_cl))
> +		return 0; /* Nothing to do */
> +
> +	cl->clocks_in_use[substream->stream] = false;
> +
> +	if (!mca_fe_clocks_in_use(fe_cl))
> +		mca_fe_disable_clocks(fe_cl);

Are you sure this doesn't need locking?

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