Re: [PATCH 2/5] ASoC: fsl_asrc: Fix handling of deferred spba clock

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found no new issues
in this patch, but noticed 1 related pre-existing issue it does not
introduce:
- [Medium] ASoC: fsl_asrc: stale register states in
  fsl_asrc_config_pair() [1]
--

commit 62ba61794f6dac52b1de47eef34f329de32edee9
Author: bui duc phuc <phucduc.bui@gmail.com>

ASoC: fsl_asrc: Fix handling of deferred spba clock

This commit updates fsl_asrc_probe() to return -EPROBE_DEFER when
devm_clk_get() for the spba clock defers, while preserving a warning for
other error codes.

> diff --git a/sound/soc/fsl/fsl_asrc.c b/sound/soc/fsl/fsl_asrc.c
> index 055593d5d37b6..c91ffb5e0c5e8 100644
> --- a/sound/soc/fsl/fsl_asrc.c
> +++ b/sound/soc/fsl/fsl_asrc.c
> @@ -1315,8 +1315,11 @@ static int fsl_asrc_probe(struct platform_device *pdev)
>  				     "failed to get ipg clock\n");
>  
>  	asrc->spba_clk = devm_clk_get(&pdev->dev, "spba");
> -	if (IS_ERR(asrc->spba_clk))
> +	if (IS_ERR(asrc->spba_clk)) {
> +		if (PTR_ERR(asrc->spba_clk) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
>  		dev_warn(&pdev->dev, "failed to get spba clock\n");
> +	}

[Severity: Medium]
This problem wasn't introduced by this patch, but can [1]
fsl_asrc_config_pair() leave hardware registers with stale values across a
warm reboot?

Earlier in fsl_asrc_probe(), devm_regmap_init_mmio() initializes the regmap
cache to all-zero defaults without issuing a hardware soft-reset first:

sound/soc/fsl/fsl_asrc.c:fsl_asrc_probe() {
	...
	asrc->regmap = devm_regmap_init_mmio(&pdev->dev, regs, &fsl_asrc_regmap_config);
	...
}

When fsl_asrc_config_pair() later calls regmap_update_bits() on REG_ASRCNCR,
REG_ASRCDR, REG_ASRMCR1, or REG_ASRCFG with a target field value of 0 (for
example, a 24-bit audio width or 1:1 clock ratio), regmap_update_bits() sees
0 in the cache and skips the register write, leaving the hardware running
with non-zero dividers and modes from the prior boot.

[1] https://sashiko.dev/#/bug/linux-75f0b96f-de73-4139-881e-4c69d6455f22

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261112105116.32274-1-phucduc.bui@gmail.com?part=2