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authorMaciej W. Rozycki <macro@linux-mips.org>2014-04-01 00:57:28 +0100
committerRalf Baechle <ralf@linux-mips.org>2014-05-13 00:29:36 +0200
commit2db4bc3418c43f1e810b304c48f8ddff2535075b (patch)
tree70aecfaca9e45a7b2685ef3fb65f0cdf3f595e3a /arch/mips/lib
parent824122a319d827d42aeb4646a3bf639937fdb2ce (diff)
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MIPS: __delay CPU_DADDI_WORKAROUNDS bug fix
With CPU_DADDI_WORKAROUNDS enabled __delay assembles with a macro in a branch delay slot: {standard input}: Assembler messages: {standard input}:18: Warning: Macro instruction expanded into multiple instructions in a branch delay slot and broken code results: 0000000000000000 <__delay>: 0: 1480ffff bnez a0,0 <__delay> 4: 24010001 li at,1 8: 0081202f dsubu a0,a0,at c: 03e00008 jr ra 10: 00000000 nop 14: 00000000 nop Consequently the function loops indefinitely, showing up prominently as a hang in the delay loop calibration at bootstrap. This change corrects the problem by forcing the immediate 1 into a register while keeping code produced identical where CPU_DADDI_WORKAROUNDS is disabled. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6669/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/lib')
-rw-r--r--arch/mips/lib/delay.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/mips/lib/delay.c b/arch/mips/lib/delay.c
index 44713af15a62..705cfb7c1a74 100644
--- a/arch/mips/lib/delay.c
+++ b/arch/mips/lib/delay.c
@@ -6,7 +6,7 @@
* Copyright (C) 1994 by Waldorf Electronics
* Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
- * Copyright (C) 2007 Maciej W. Rozycki
+ * Copyright (C) 2007, 2014 Maciej W. Rozycki
*/
#include <linux/module.h>
#include <linux/param.h>
@@ -15,6 +15,12 @@
#include <asm/compiler.h>
#include <asm/war.h>
+#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
+#define GCC_DADDI_IMM_ASM() "I"
+#else
+#define GCC_DADDI_IMM_ASM() "r"
+#endif
+
void __delay(unsigned long loops)
{
__asm__ __volatile__ (
@@ -22,13 +28,13 @@ void __delay(unsigned long loops)
" .align 3 \n"
"1: bnez %0, 1b \n"
#if BITS_PER_LONG == 32
- " subu %0, 1 \n"
+ " subu %0, %1 \n"
#else
- " dsubu %0, 1 \n"
+ " dsubu %0, %1 \n"
#endif
" .set reorder \n"
: "=r" (loops)
- : "0" (loops));
+ : GCC_DADDI_IMM_ASM() (1), "0" (loops));
}
EXPORT_SYMBOL(__delay);