[alsa-devel] [PATCH] ASoC: prevent compilers from optimising pll calculation into __aeabi__uldivmod

[Barry Song]

From: Barry Song <21cnbao at gmail.com>

The newest compiliers can optimize pll calculation in several codecs into __aeabi__uldivmod which doesn't exist in kernel.
Then the link will fail:
ERROR: "__aeabi_uldivmod" [sound/soc/codecs/snd-soc-wm8974.ko] undefined!
ERROR: "__aeabi_uldivmod" [sound/soc/codecs/snd-soc-wm8940.ko] undefined!
ERROR: "__aeabi_uldivmod" [sound/soc/codecs/snd-soc-wm8510.ko] undefined!
This patch prevent the optimizaton by insert ASM.

Signed-off-by: Barry Song <21cnbao at gmail.com>
Cc: Zhiwu Song <zhiwu.song at csr.com>
Cc: Binghua Duan <binghua.duan at csr.com>
---
 sound/soc/codecs/wm8510.c |    6 ++++++
 sound/soc/codecs/wm8940.c |    6 ++++++
 sound/soc/codecs/wm8974.c |    6 ++++++
 3 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/sound/soc/codecs/wm8510.c b/sound/soc/codecs/wm8510.c
index db0dced..a636b15 100644
--- a/sound/soc/codecs/wm8510.c
+++ b/sound/soc/codecs/wm8510.c
@@ -258,6 +258,12 @@ static void pll_factors(unsigned int target, unsigned int source)
 	Nmod = target % source;
 	Kpart = FIXED_PLL_SIZE * (long long)Nmod;
 
+	/*
+	 * The following asm() prevents the compiler from optimising
+	 * into a standard EABI function __aeabi__uldivmod()
+	 */
+	asm("" : "+r"(source));
+
 	do_div(Kpart, source);
 
 	K = Kpart & 0xFFFFFFFF;
diff --git a/sound/soc/codecs/wm8940.c b/sound/soc/codecs/wm8940.c
index 25580e3..f6148af 100644
--- a/sound/soc/codecs/wm8940.c
+++ b/sound/soc/codecs/wm8940.c
@@ -520,6 +520,12 @@ static void pll_factors(unsigned int target, unsigned int source)
 	Nmod = target % source;
 	Kpart = FIXED_PLL_SIZE * (long long)Nmod;
 
+	/*
+	 * The following asm() prevents the compiler from optimising
+	 * into a standard EABI function __aeabi__uldivmod()
+	 */
+	asm("" : "+r"(source));
+
 	do_div(Kpart, source);
 
 	K = Kpart & 0xFFFFFFFF;
diff --git a/sound/soc/codecs/wm8974.c b/sound/soc/codecs/wm8974.c
index ca646a8..c9036d9 100644
--- a/sound/soc/codecs/wm8974.c
+++ b/sound/soc/codecs/wm8974.c
@@ -317,6 +317,12 @@ static void pll_factors(struct pll_ *pll_div,
 	Nmod = target % source;
 	Kpart = FIXED_PLL_SIZE * (long long)Nmod;
 
+	/*
+	 * The following asm() prevents the compiler from optimising
+	 * into a standard EABI function __aeabi__uldivmod()
+	 */
+	asm("" : "+r"(source));
+
 	do_div(Kpart, source);
 
 	K = Kpart & 0xFFFFFFFF;
-- 
1.7.1



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