[PATCH] ASoC: sophgo: fix 64-bit division build failure

[PATCH] ASoC: sophgo: fix 64-bit division build failure

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

cv1800b_adc_setbclk_div() does four 64-bit divisions in a row, which
is rather inefficient on 32-bit systems, and using the plain division
causes a build failure as a result:

ERROR: modpost: "__aeabi_uldivmod" [sound/soc/sophgo/cv1800b-sound-adc.ko] undefined!

Consolidate those into a single division using the div_u64() macro.

Fixes: 4cf8752a03e6 ("ASoC: sophgo: add CV1800B internal ADC codec driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 sound/soc/sophgo/cv1800b-sound-adc.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/sound/soc/sophgo/cv1800b-sound-adc.c b/sound/soc/sophgo/cv1800b-sound-adc.c
index 794030b713e9..b66761156b99 100644
--- a/sound/soc/sophgo/cv1800b-sound-adc.c
+++ b/sound/soc/sophgo/cv1800b-sound-adc.c
@@ -105,11 +105,8 @@ static int cv1800b_adc_setbclk_div(struct cv1800b_priv *priv, unsigned int rate)
 	if (!priv->mclk_rate || !rate)
 		return -EINVAL;
 
-	tmp = priv->mclk_rate;
-	tmp /= CV1800B_RXADC_WORD_LEN;
-	tmp /= CV1800B_RXADC_CHANNELS;
-	tmp /= rate;
-	tmp /= 2;
+	tmp = div_u64(priv->mclk_rate, CV1800B_RXADC_WORD_LEN *
+		      CV1800B_RXADC_CHANNELS * rate * 2);
 
 	if (!tmp) {
 		dev_err(priv->dev, "computed BCLK divider is zero\n");
-- 
2.39.5

Re: [PATCH] ASoC: sophgo: fix 64-bit division build failure

[Alexander Sverdlin]

Hi Arnd!

On Mon, 2026-02-02 at 10:53 +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> cv1800b_adc_setbclk_div() does four 64-bit divisions in a row, which

3 of the 4 divisors are actually a power of two, so it would be a bug
in the compiler to issue a division for them...

Regarding the 64 bits: seems that the actual issue is the tmp variable that
is of u64 type for no reason, because priv->mclk_rate is only u32.

Maybe turning tmp into a u32 would avoid unnecessary 64-bit division
altogether?

> is rather inefficient on 32-bit systems, and using the plain division
> causes a build failure as a result:
> 
> ERROR: modpost: "__aeabi_uldivmod" [sound/soc/sophgo/cv1800b-sound-adc.ko] undefined!
> 
> Consolidate those into a single division using the div_u64() macro.
> 
> Fixes: 4cf8752a03e6 ("ASoC: sophgo: add CV1800B internal ADC codec driver")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  sound/soc/sophgo/cv1800b-sound-adc.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/sound/soc/sophgo/cv1800b-sound-adc.c b/sound/soc/sophgo/cv1800b-sound-adc.c
> index 794030b713e9..b66761156b99 100644
> --- a/sound/soc/sophgo/cv1800b-sound-adc.c
> +++ b/sound/soc/sophgo/cv1800b-sound-adc.c
> @@ -105,11 +105,8 @@ static int cv1800b_adc_setbclk_div(struct cv1800b_priv *priv, unsigned int rate)
>  	if (!priv->mclk_rate || !rate)
>  		return -EINVAL;
>  
> -	tmp = priv->mclk_rate;
> -	tmp /= CV1800B_RXADC_WORD_LEN;
> -	tmp /= CV1800B_RXADC_CHANNELS;
> -	tmp /= rate;
> -	tmp /= 2;
> +	tmp = div_u64(priv->mclk_rate, CV1800B_RXADC_WORD_LEN *
> +		      CV1800B_RXADC_CHANNELS * rate * 2);
>  
>  	if (!tmp) {
>  		dev_err(priv->dev, "computed BCLK divider is zero\n");

-- 
Alexander Sverdlin.

Re: [PATCH] ASoC: sophgo: fix 64-bit division build failure

[Arnd Bergmann]

On Mon, Feb 2, 2026, at 22:31, Alexander Sverdlin wrote:
> Regarding the 64 bits: seems that the actual issue is the tmp variable that
> is of u64 type for no reason, because priv->mclk_rate is only u32.
>
> Maybe turning tmp into a u32 would avoid unnecessary 64-bit division
> altogether?

Ah, good point, sent v2 now.

      Arnd

Re: [PATCH] ASoC: sophgo: fix 64-bit division build failure

[Mark Brown]

On Mon, 02 Feb 2026 10:53:14 +0100, Arnd Bergmann wrote:
> cv1800b_adc_setbclk_div() does four 64-bit divisions in a row, which
> is rather inefficient on 32-bit systems, and using the plain division
> causes a build failure as a result:
> 
> ERROR: modpost: "__aeabi_uldivmod" [sound/soc/sophgo/cv1800b-sound-adc.ko] undefined!
> 
> Consolidate those into a single division using the div_u64() macro.
> 
> [...]

Applied to

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

Thanks!

[1/1] ASoC: sophgo: fix 64-bit division build failure
      commit: cad9720dd7e4dcdaec8e854fb2c1d1d45fd6dbad

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

Re: [PATCH] ASoC: sophgo: fix 64-bit division build failure

[Chen Wang]

On 2/3/2026 6:48 AM, Mark Brown wrote:
> On Mon, 02 Feb 2026 10:53:14 +0100, Arnd Bergmann wrote:
>> cv1800b_adc_setbclk_div() does four 64-bit divisions in a row, which
>> is rather inefficient on 32-bit systems, and using the plain division
>> causes a build failure as a result:
>>
>> ERROR: modpost: "__aeabi_uldivmod" [sound/soc/sophgo/cv1800b-sound-adc.ko] undefined!
>>
>> Consolidate those into a single division using the div_u64() macro.
>>
>> [...]
> Applied to
>
>     https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
>
> Thanks!
>
> [1/1] ASoC: sophgo: fix 64-bit division build failure
>        commit: cad9720dd7e4dcdaec8e854fb2c1d1d45fd6dbad
>
> 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
>
Hi, Mark,

I noticed Arnd sent v2 for this patch, please see 
https://lore.kernel.org/sophgo/20260202215956.2127414-1-arnd@kernel.org/.

Chen