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From: Jeff Hansen <jhansen@cardaccess-inc.com>
Subject: [PATCH] kmap_coherent
On ASUS WL-500gP there are some "Data bus error"s when executing simple
commands liks "ps" or "cat /proc/1/cmdline".
This fixes OpenWrt ticket #1485: https://dev.openwrt.org/ticket/1485
---
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -226,6 +226,9 @@
#ifndef cpu_has_local_ebase
#define cpu_has_local_ebase 1
#endif
+#ifndef cpu_use_kmap_coherent
+#define cpu_use_kmap_coherent 1
+#endif
/*
* I-Cache snoops remote store. This only matters on SMP. Some multiprocessors
--- a/arch/mips/include/asm/mach-bcm47xx/cpu-feature-overrides.h
+++ b/arch/mips/include/asm/mach-bcm47xx/cpu-feature-overrides.h
@@ -80,4 +80,6 @@
#define cpu_scache_line_size() 0
#define cpu_has_vz 0
+#define cpu_use_kmap_coherent 0
+
#endif /* __ASM_MACH_BCM47XX_CPU_FEATURE_OVERRIDES_H */
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -694,7 +694,7 @@ static inline void local_r4k_flush_cache
map_coherent = (cpu_has_dc_aliases &&
page_mapcount(page) &&
!Page_dcache_dirty(page));
- if (map_coherent)
+ if (map_coherent && cpu_use_kmap_coherent)
vaddr = kmap_coherent(page, addr);
else
vaddr = kmap_atomic(page);
@@ -719,7 +719,7 @@ static inline void local_r4k_flush_cache
}
if (vaddr) {
- if (map_coherent)
+ if (map_coherent && cpu_use_kmap_coherent)
kunmap_coherent();
else
kunmap_atomic(vaddr);
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -168,7 +168,7 @@ void copy_user_highpage(struct page *to,
void *vfrom, *vto;
vto = kmap_atomic(to);
- if (cpu_has_dc_aliases &&
+ if (cpu_has_dc_aliases && cpu_use_kmap_coherent &&
page_mapcount(from) && !Page_dcache_dirty(from)) {
vfrom = kmap_coherent(from, vaddr);
copy_page(vto, vfrom);
@@ -190,7 +190,7 @@ void copy_to_user_page(struct vm_area_st
struct page *page, unsigned long vaddr, void *dst, const void *src,
unsigned long len)
{
- if (cpu_has_dc_aliases &&
+ if (cpu_has_dc_aliases && cpu_use_kmap_coherent &&
page_mapcount(page) && !Page_dcache_dirty(page)) {
void *vto = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
memcpy(vto, src, len);
@@ -208,7 +208,7 @@ void copy_from_user_page(struct vm_area_
struct page *page, unsigned long vaddr, void *dst, const void *src,
unsigned long len)
{
- if (cpu_has_dc_aliases &&
+ if (cpu_has_dc_aliases && cpu_use_kmap_coherent &&
page_mapcount(page) && !Page_dcache_dirty(page)) {
void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
memcpy(dst, vfrom, len);
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