ASoC: pxa: remove incorrect do_div() call

The new optimized do_div implementation (now in asm-generic/next) exposes a glitch in the brownstone audio driver by producing a compile-time warning:

sound/soc/pxa/brownstone.c: In function 'brownstone_wm8994_hw_params':
sound/soc/pxa/brownstone.c:67:85: warning: comparison of distinct pointer types lacks a cast sound/soc/pxa/brownstone.c:67:10125: warning: right shift count >= width of type [-Wshift-count-overflow] sound/soc/pxa/brownstone.c:67:10254: warning: passing argument 1 of '__div64_32' from incompatible pointer type [-Wincompatible-pointer-types]

The driver just divides two plain integer values, so it should not use do_div to start with, but has apparently done so ever since the code was first merged. This replaces do_div with a simple division operator.

---
I think this one is harmless, so we only need it in 4.5 to avoid the warning, but not backported to earlier kernels.

Found today on ARM allmodconfig

index 6147e86e9b0f..416ea646c3b1 100644
@@ -63,8 +63,7 @@ static int brownstone_wm8994_hw_params(struct snd_pcm_substream *substream,
 		sysclk    = params_rate(params) * 512;
 		sspa_mclk = params_rate(params) * 64;
 	}
-	sspa_div = freq_out;
-	do_div(sspa_div, sspa_mclk);
+	sspa_div = freq_out / sspa_mclk;
 
 	snd_soc_dai_set_sysclk(cpu_dai, MMP_SSPA_CLK_AUDIO, freq_out, 0);
 	snd_soc_dai_set_pll(cpu_dai, MMP_SYSCLK, 0, freq_out, sysclk);

The patch

ASoC: pxa: remove incorrect do_div() call

has been applied to the asoc tree at

git://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: Arnd Bergmann <[email protected]>
Date: Fri, 20 Nov 2015 10:32:44 +0100
Subject: [PATCH] ASoC: pxa: remove incorrect do_div() call

The new optimized do_div implementation (now in asm-generic/next) exposes a glitch in the brownstone audio driver by producing a compile-time warning:

sound/soc/pxa/brownstone.c: In function 'brownstone_wm8994_hw_params':
sound/soc/pxa/brownstone.c:67:85: warning: comparison of distinct pointer types lacks a cast sound/soc/pxa/brownstone.c:67:10125: warning: right shift count >= width of type [-Wshift-count-overflow] sound/soc/pxa/brownstone.c:67:10254: warning: passing argument 1 of '__div64_32' from incompatible pointer type [-Wincompatible-pointer-types]

The driver just divides two plain integer values, so it should not use do_div to start with, but has apparently done so ever since the code was first merged. This replaces do_div with a simple division operator.

---
 sound/soc/pxa/brownstone.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index 6147e86e9b0f..416ea646c3b1 100644
@@ -63,8 +63,7 @@ static int brownstone_wm8994_hw_params(struct snd_pcm_substream *substream,
 		sysclk    = params_rate(params) * 512;
 		sspa_mclk = params_rate(params) * 64;
 	}
-	sspa_div = freq_out;
-	do_div(sspa_div, sspa_mclk);
+	sspa_div = freq_out / sspa_mclk;
 
 	snd_soc_dai_set_sysclk(cpu_dai, MMP_SSPA_CLK_AUDIO, freq_out, 0);
 	snd_soc_dai_set_pll(cpu_dai, MMP_SYSCLK, 0, freq_out, sysclk);

2.6.2

Good idea. I see that Mark has already applied the original patch, and with my new version, gcc should be smart enough to completely optimize out the division and the unused variable. This means the effect of the patch is very small, but if Mark wants it, he can apply the below.

Arnd

8<---
Subject: ASoC: remove unused variable

As pointed out by Zhangfei Gao, the sspa_div variable in brownstone_wm8994_hw_params() is completely unused, so as a cleanup following a prior patch, this removes both the variable and the division.

index 416ea646c3b1..ec522e94b0e2 100644
@@ -52,7 +52,6 @@ static int brownstone_wm8994_hw_params(struct snd_pcm_substream *substream,
 	struct snd_soc_dai *codec_dai = rtd->codec_dai;
 	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
 	int freq_out, sspa_mclk, sysclk;
-	int sspa_div;
 
 	if (params_rate(params) > 11025) {
 		freq_out  = params_rate(params) * 512;

@@ -63,7 +62,6 @@ static int brownstone_wm8994_hw_params(struct snd_pcm_substream *substream,
 		sysclk    = params_rate(params) * 512;
 		sspa_mclk = params_rate(params) * 64;
 	}
-	sspa_div = freq_out / sspa_mclk;
 
 	snd_soc_dai_set_sysclk(cpu_dai, MMP_SSPA_CLK_AUDIO, freq_out, 0);
 	snd_soc_dai_set_pll(cpu_dai, MMP_SYSCLK, 0, freq_out, sysclk);

The patch

ASoC: pxa: remove unused variable

has been applied to the asoc tree at

git://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: Arnd Bergmann <[email protected]>
Date: Thu, 25 Feb 2016 23:02:04 +0100
Subject: [PATCH] ASoC: pxa: remove unused variable

As pointed out by Zhangfei Gao, the sspa_div variable in brownstone_wm8994_hw_params() is completely unused, so as a cleanup following a prior patch, this removes both the variable and the division.

---
 sound/soc/pxa/brownstone.c | 2 --
 1 file changed, 2 deletions(-)

index 416ea646c3b1..ec522e94b0e2 100644
@@ -52,7 +52,6 @@ static int brownstone_wm8994_hw_params(struct snd_pcm_substream *substream,
 	struct snd_soc_dai *codec_dai = rtd->codec_dai;
 	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
 	int freq_out, sspa_mclk, sysclk;
-	int sspa_div;
 
 	if (params_rate(params) > 11025) {
 		freq_out  = params_rate(params) * 512;

@@ -63,7 +62,6 @@ static int brownstone_wm8994_hw_params(struct snd_pcm_substream *substream,
 		sysclk    = params_rate(params) * 512;
 		sspa_mclk = params_rate(params) * 64;
 	}
-	sspa_div = freq_out / sspa_mclk;
 
 	snd_soc_dai_set_sysclk(cpu_dai, MMP_SSPA_CLK_AUDIO, freq_out, 0);
 	snd_soc_dai_set_pll(cpu_dai, MMP_SYSCLK, 0, freq_out, sysclk);

2.7.0