linux-kernel - [PATCH] ASoC: pxa: remove incorrect do

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Message-ID: <7580645.enu4DmUPIv@wuerfel>
Date:	Fri, 20 Nov 2015 10:32:44 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	alsa-devel@...a-project.org, broonie@...nel.org
Cc:	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Daniel Mack <daniel@...que.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Leo Yan <leoy@...vell.com>,
	Zhangfei Gao <zhangfei.gao@...aro.org>
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.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
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

diff --git a/sound/soc/pxa/brownstone.c b/sound/soc/pxa/brownstone.c
index 6147e86e9b0f..416ea646c3b1 100644
--- a/sound/soc/pxa/brownstone.c
+++ b/sound/soc/pxa/brownstone.c
@@ -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);

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