From: Arnd Bergmann <arnd@arndb.de>
To: alsa-devel@alsa-project.org, broonie@kernel.org
Cc: Robert Jarzmik <robert.jarzmik@free.fr>,
        Haojian Zhuang <haojian.zhuang@gmail.com>,
        Daniel Mack <daniel@zonque.org>, Liam Girdwood <lgirdwood@gmail.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Leo Yan <leoy@marvell.com>, Zhangfei Gao <zhangfei.gao@linaro.org>
Subject: [PATCH] ASoC: pxa: remove incorrect do_div() call
Date: Fri, 20 Nov 2015 10:32:44 +0100
Message-ID: <7580645.enu4DmUPIv@wuerfel>
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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@arndb.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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