[PATCH] ASoC: fsl_esai: Fix divisor calculation failure at lower ratio

[PATCH] ASoC: fsl_esai: Fix divisor calculation failure at lower ratio

[Nicolin Chen]

When the desired ratio is less than 256, the savesub (tolerance)
in the calculation would become 0. This will then fail the loop-
search immediately without reporting any errors.

But if the ratio is smaller enough, there is no need to calculate
the tolerance because PM divisor alone is enough to get the ratio.

So a simple fix could be just to set PM directly instead of going
into the loop-search.

Reported-by: Marek Vasut <marex@denx.de>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: Marek Vasut <marex@denx.de>
---
 sound/soc/fsl/fsl_esai.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
index 40a7004..da8fd98 100644
--- a/sound/soc/fsl/fsl_esai.c
+++ b/sound/soc/fsl/fsl_esai.c
@@ -144,6 +144,13 @@ static int fsl_esai_divisor_cal(struct snd_soc_dai *dai, bool tx, u32 ratio,
 
 	psr = ratio <= 256 * maxfp ? ESAI_xCCR_xPSR_BYPASS : ESAI_xCCR_xPSR_DIV8;
 
+	/* Do not loop-search if PM (1 ~ 256) alone can serve the ratio */
+	if (ratio <= 256) {
+		pm = ratio;
+		fp = 1;
+		goto out;
+	}
+
 	/* Set the max fluctuation -- 0.1% of the max devisor */
 	savesub = (psr ? 1 : 8)  * 256 * maxfp / 1000;
 
-- 
2.7.4

Re: [alsa-devel] [PATCH] ASoC: fsl_esai: Fix divisor calculation failure at lower ratio

[Fabio Estevam]

Hi Nicolin,

On Sun, Apr 8, 2018 at 8:57 PM, Nicolin Chen <nicoleotsuka@gmail.com> wrote:
> When the desired ratio is less than 256, the savesub (tolerance)
> in the calculation would become 0. This will then fail the loop-
> search immediately without reporting any errors.
>
> But if the ratio is smaller enough, there is no need to calculate
> the tolerance because PM divisor alone is enough to get the ratio.
>
> So a simple fix could be just to set PM directly instead of going
> into the loop-search.
>
> Reported-by: Marek Vasut <marex@denx.de>
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> Cc: Marek Vasut <marex@denx.de>

If this fixes Marek's usecase then I think we should also add:

Cc: <stable@vger.kernel.org>

Thanks

Re: [PATCH] ASoC: fsl_esai: Fix divisor calculation failure at lower ratio

[Marek Vasut]

On 04/09/2018 01:57 AM, Nicolin Chen wrote:
> When the desired ratio is less than 256, the savesub (tolerance)
> in the calculation would become 0. This will then fail the loop-
> search immediately without reporting any errors.
> 
> But if the ratio is smaller enough, there is no need to calculate
> the tolerance because PM divisor alone is enough to get the ratio.
> 
> So a simple fix could be just to set PM directly instead of going
> into the loop-search.
> 
> Reported-by: Marek Vasut <marex@denx.de>
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> Cc: Marek Vasut <marex@denx.de>

On i.MX6Q with TI PCM1808
Tested-by: Marek Vasut <marex@denx.de>

> ---
>  sound/soc/fsl/fsl_esai.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
> index 40a7004..da8fd98 100644
> --- a/sound/soc/fsl/fsl_esai.c
> +++ b/sound/soc/fsl/fsl_esai.c
> @@ -144,6 +144,13 @@ static int fsl_esai_divisor_cal(struct snd_soc_dai *dai, bool tx, u32 ratio,
>  
>  	psr = ratio <= 256 * maxfp ? ESAI_xCCR_xPSR_BYPASS : ESAI_xCCR_xPSR_DIV8;
>  
> +	/* Do not loop-search if PM (1 ~ 256) alone can serve the ratio */
> +	if (ratio <= 256) {
> +		pm = ratio;
> +		fp = 1;
> +		goto out;
> +	}
> +
>  	/* Set the max fluctuation -- 0.1% of the max devisor */
>  	savesub = (psr ? 1 : 8)  * 256 * maxfp / 1000;
>  
> 


-- 
Best regards,
Marek Vasut

Re: [alsa-devel] [PATCH] ASoC: fsl_esai: Fix divisor calculation failure at lower ratio

[Fabio Estevam]

Hi Nicolin,

On Sun, Apr 8, 2018 at 8:57 PM, Nicolin Chen <nicoleotsuka@gmail.com> wrote:
> When the desired ratio is less than 256, the savesub (tolerance)
> in the calculation would become 0. This will then fail the loop-
> search immediately without reporting any errors.
>
> But if the ratio is smaller enough, there is no need to calculate
> the tolerance because PM divisor alone is enough to get the ratio.
>
> So a simple fix could be just to set PM directly instead of going
> into the loop-search.
>
> Reported-by: Marek Vasut <marex@denx.de>
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> Cc: Marek Vasut <marex@denx.de>

Thanks for the fix:

Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

Applied "ASoC: fsl_esai: Fix divisor calculation failure at lower ratio" to the asoc tree

[Mark Brown]

The patch

   ASoC: fsl_esai: Fix divisor calculation failure at lower ratio

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From c656941df9bc80f7ec65b92ca73c42f8b0b62628 Mon Sep 17 00:00:00 2001
From: Nicolin Chen <nicoleotsuka@gmail.com>
Date: Sun, 8 Apr 2018 16:57:35 -0700
Subject: [PATCH] ASoC: fsl_esai: Fix divisor calculation failure at lower
 ratio

When the desired ratio is less than 256, the savesub (tolerance)
in the calculation would become 0. This will then fail the loop-
search immediately without reporting any errors.

But if the ratio is smaller enough, there is no need to calculate
the tolerance because PM divisor alone is enough to get the ratio.

So a simple fix could be just to set PM directly instead of going
into the loop-search.

Reported-by: Marek Vasut <marex@denx.de>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Tested-by: Marek Vasut <marex@denx.de>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
---
 sound/soc/fsl/fsl_esai.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
index 40a700493f4c..da8fd98c7f51 100644
--- a/sound/soc/fsl/fsl_esai.c
+++ b/sound/soc/fsl/fsl_esai.c
@@ -144,6 +144,13 @@ static int fsl_esai_divisor_cal(struct snd_soc_dai *dai, bool tx, u32 ratio,
 
 	psr = ratio <= 256 * maxfp ? ESAI_xCCR_xPSR_BYPASS : ESAI_xCCR_xPSR_DIV8;
 
+	/* Do not loop-search if PM (1 ~ 256) alone can serve the ratio */
+	if (ratio <= 256) {
+		pm = ratio;
+		fp = 1;
+		goto out;
+	}
+
 	/* Set the max fluctuation -- 0.1% of the max devisor */
 	savesub = (psr ? 1 : 8)  * 256 * maxfp / 1000;
 
-- 
2.17.0