linux-kernel - Re: [PATCH] ASoC: tegra: Fix build error due to 64-by-32 division

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Message-ID: <18d56fcb-29b1-fbc9-f9cd-7706f65c678d@infradead.org>
Date:   Thu, 23 Jul 2020 13:33:16 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Sameer Pujar <spujar@...dia.com>, broonie@...nel.org,
        lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.com,
        geert@...ux-m68k.org
Cc:     thierry.reding@...il.com, jonathanh@...dia.com,
        alsa-devel@...a-project.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: tegra: Fix build error due to 64-by-32 division

On 7/23/20 1:13 AM, Sameer Pujar wrote:
> Build errors are seen on 32-bit platforms because of a plain 64-by-32
> division. For example, following build erros were reported.
> 
> "ERROR: modpost: "__udivdi3" [sound/soc/tegra/snd-soc-tegra210-dmic.ko]
>  undefined!"
> "ERROR: modpost: "__divdi3" [sound/soc/tegra/snd-soc-tegra210-dmic.ko]
>  undefined!"
> 
> This can be fixed by using div_u64() helper from 'math64.h' header.
> 
> Fixes: 8c8ff982e9e2 ("ASoC: tegra: Add Tegra210 based DMIC driver")
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Signed-off-by: Sameer Pujar <spujar@...dia.com>
> ---
>  sound/soc/tegra/tegra210_dmic.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/soc/tegra/tegra210_dmic.c b/sound/soc/tegra/tegra210_dmic.c
> index ff6fd65..d682414 100644
> --- a/sound/soc/tegra/tegra210_dmic.c
> +++ b/sound/soc/tegra/tegra210_dmic.c
> @@ -6,6 +6,7 @@
>  
>  #include <linux/clk.h>
>  #include <linux/device.h>
> +#include <linux/math64.h>
>  #include <linux/module.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
> @@ -129,7 +130,7 @@ static int tegra210_dmic_hw_params(struct snd_pcm_substream *substream,
>  	 * Boost Gain Volume control has 100x factor.
>  	 */
>  	if (dmic->boost_gain)
> -		gain_q23 = (gain_q23 * dmic->boost_gain) / 100;
> +		gain_q23 = div_u64(gain_q23 * dmic->boost_gain, 100);
>  
>  	regmap_write(dmic->regmap, TEGRA210_DMIC_LP_FILTER_GAIN,
>  		     (unsigned int)gain_q23);
> 

Yes, that fixes the division problem. Thanks.
Acked-by: Randy Dunlap <rdunlap@...radead.org>


Now I get these warnings:

  CC [M]  sound/soc/tegra/tegra210_dmic.o
../sound/soc/tegra/tegra210_dmic.c:55:12: warning: ‘tegra210_dmic_runtime_resume’ defined but not used [-Wunused-function]
 static int tegra210_dmic_runtime_resume(struct device *dev)
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
../sound/soc/tegra/tegra210_dmic.c:43:12: warning: ‘tegra210_dmic_runtime_suspend’ defined but not used [-Wunused-function]
 static int tegra210_dmic_runtime_suspend(struct device *dev)
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~


-- 
~Randy
Reported-by: Randy Dunlap <rdunlap@...radead.org>