[alsa-devel] [PATCH V2 1/3] ASoC: bcm2835: move to use the clock framework

[Eric Anholt]

kernel at martin.sperl.org writes:

> From: Martin Sperl <kernel at martin.sperl.org>
>
> Since the move to the new clock framework with commit 94cb7f76caa0
> ("ARM: bcm2835: Switch to using the new clock driver support.")
> this driver was no longer functional as it was manipulating the
> clock registers locally without going true the framework.
>
> This patch moves to use the new clock framework and also
> moves away from the hardcoded address offsets for DMA getting
> the dma-address directly from the device tree.
>
> Note that the optimal bclk_ratio selection to avoid jitter
> due to the use of fractional dividers, which is in the
> current version has been removed, because not all devices
> support these non power of 2 sized transfers, which resulted
> in lots of (downstream) modules that use:
>   snd_soc_dai_set_bclk_ratio(cpu_dai, sample_bits * 2);
>
> Signed-off-by: Martin Sperl <kernel at martin.sperl.org>
> ---
>  sound/soc/bcm/bcm2835-i2s.c |  284 ++++++++++---------------------------------
>  1 file changed, 64 insertions(+), 220 deletions(-)
>
> diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c
> index 3303d5f..1c1f221 100644
> --- a/sound/soc/bcm/bcm2835-i2s.c
> +++ b/sound/soc/bcm/bcm2835-i2s.c

> -	dev->i2s_regmap = regmap[0];
> -	dev->clk_regmap = regmap[1];
> +	/* get the clock */
> +	dev->clk_prepared = false;
> +	dev->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(dev->clk)) {
> +		dev_err(&pdev->dev, "could not get clk: %ld\n",
> +			PTR_ERR(dev->clk));
> +		return PTR_ERR(dev->clk);
> +	}
> +
> +	/* Request ioarea */
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(&pdev->dev, mem);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	dev->i2s_regmap = devm_regmap_init_mmio(&pdev->dev, base,
> +				&bcm2835_regmap_config);
> +	if (IS_ERR(dev->i2s_regmap))
> +		return PTR_ERR(dev->i2s_regmap);
> +
> +	/* Set the DMA address - we have to parse DT ourselves */
> +	addr = of_get_address(pdev->dev.of_node, 0, NULL, NULL);
> +	if (!addr) {
> +		dev_err(&pdev->dev, "could not get DMA-register address\n");
> +		return -EINVAL;
> +	}
> +	dma_base = be32_to_cpup(addr);

Why aren't we just using mem->start like before?  That seems like an
independent change that should be justified on its own.  I'd be ready to
ack the patch if that change is removed.

I'm also trying to work my way through the clock changes.
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