linux-kernel - Re: [PATCH] ALSA: at73c213: manage SSC clock

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Message-ID: <yw1xegdgtgfs.fsf@unicorn.mansr.com>
Date:	Sun, 17 Jan 2016 14:43:19 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Hans-Christian Egtvedt <egtvedt@...fundet.no>
Cc:	linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
	Takashi Iwai <tiwai@...e.com>
Subject: Re: [PATCH] ALSA: at73c213: manage SSC clock

Mans Rullgard <mans@...sr.com> writes:

> Since commit 49af54ff0fc7 ("misc: atmel-ssc: prepare clock only when
> request") the SSC driver expects clients to manage the SSC clock.
> Update this driver accordingly.
>
> Signed-off-by: Mans Rullgard <mans@...sr.com>
> ---
>  sound/spi/at73c213.c | 8 ++++++++
>  1 file changed, 8 insertions(+)

On second thoughts, please disregard this patch.  It's better to enable
the clock only when it is actually required.

> diff --git a/sound/spi/at73c213.c b/sound/spi/at73c213.c
> index 39522367897c..3b2d0b2be421 100644
> --- a/sound/spi/at73c213.c
> +++ b/sound/spi/at73c213.c
> @@ -981,6 +981,8 @@ static int snd_at73c213_probe(struct spi_device *spi)
>  		goto out_card;
>  	}
>
> +	clk_enable(chip->ssc->clk);
> +
>  	retval = snd_at73c213_dev_init(card, spi);
>  	if (retval)
>  		goto out_ssc;
> @@ -998,6 +1000,7 @@ static int snd_at73c213_probe(struct spi_device *spi)
>  	goto out;
>
>  out_ssc:
> +	clk_disable(chip->ssc->clk);
>  	ssc_free(chip->ssc);
>  out_card:
>  	snd_card_free(card);
> @@ -1066,6 +1069,9 @@ out:
>  	/* Stop DAC master clock. */
>  	clk_disable(chip->board->dac_clk);
>
> +	/* Stop SSC clock. */
> +	clk_disable(chip->ssc->clk);
> +
>  	ssc_free(chip->ssc);
>  	snd_card_free(card);
>
> @@ -1080,6 +1086,7 @@ static int snd_at73c213_suspend(struct device *dev)
>  	struct snd_at73c213 *chip = card->private_data;
>
>  	ssc_writel(chip->ssc->regs, CR, SSC_BIT(CR_TXDIS));
> +	clk_disable(chip->ssc->clk);
>  	clk_disable(chip->board->dac_clk);
>
>  	return 0;
> @@ -1091,6 +1098,7 @@ static int snd_at73c213_resume(struct device *dev)
>  	struct snd_at73c213 *chip = card->private_data;
>
>  	clk_enable(chip->board->dac_clk);
> +	clk_enable(chip->ssc->clk);
>  	ssc_writel(chip->ssc->regs, CR, SSC_BIT(CR_TXEN));
>
>  	return 0;
> -- 
> 2.7.0
>

-- 
Måns Rullgård