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authorHuacai Chen <chenhc@lemote.com>2018-09-05 17:33:01 +0800
committerPaul Burton <paul.burton@mips.com>2018-09-18 16:21:52 -0700
commitc824ad164760484f709daa1339df40a184f4170a (patch)
tree9c824ca14aff39d91570f261a18a43f2603de7ec /arch/mips
parent2794f688b2c336e0da85e9f91fed33febbd9f54a (diff)
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MIPS: Loongson-3: Enable Store Fill Buffer at runtime
New Loongson-3 (Loongson-3A R2, Loongson-3A R3, and newer) has SFB (Store Fill Buffer) which can improve the performance of memory access. Now, SFB enablement is controlled by CONFIG_LOONGSON3_ENHANCEMENT, and the generic kernel has no benefit from SFB (even it is running on a new Loongson-3 machine). With this patch, we can enable SFB at runtime by detecting the CPU type (the expense is war_io_reorder_wmb() will always be a 'sync', which will hurt the performance of old Loongson-3). [paul.burton@mips.com: Further info from Huacai: In practise, I found that sometimes there are boot failures if I enable SFB/LPA in cpu_probe(). I don't know why because processor designers also haven't give me an explaination, but I think this may have some relationships to speculative execution.] Signed-off-by: Huacai Chen <chenhc@lemote.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/20426/ Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@linux-mips.org Cc: Fuxin Zhang <zhangfx@lemote.com> Cc: Zhangjin Wu <wuzhangjin@gmail.com> Cc: Huacai Chen <chenhuacai@gmail.com>
Diffstat (limited to 'arch/mips')
-rw-r--r--arch/mips/include/asm/io.h2
-rw-r--r--arch/mips/include/asm/mach-loongson64/kernel-entry-init.h16
2 files changed, 13 insertions, 5 deletions
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 44f766b6b5af..eb357c92c8ee 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -289,7 +289,7 @@ static inline void iounmap(const volatile void __iomem *addr)
#undef __IS_KSEG1
}
-#if defined(CONFIG_CPU_CAVIUM_OCTEON) || defined(CONFIG_LOONGSON3_ENHANCEMENT)
+#if defined(CONFIG_CPU_CAVIUM_OCTEON) || defined(CONFIG_CPU_LOONGSON3)
#define war_io_reorder_wmb() wmb()
#else
#define war_io_reorder_wmb() barrier()
diff --git a/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h b/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h
index 312739117bb0..cbac603ced19 100644
--- a/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h
+++ b/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h
@@ -11,6 +11,8 @@
#ifndef __ASM_MACH_LOONGSON64_KERNEL_ENTRY_H
#define __ASM_MACH_LOONGSON64_KERNEL_ENTRY_H
+#include <asm/cpu.h>
+
/*
* Override macros used in arch/mips/kernel/head.S.
*/
@@ -26,12 +28,15 @@
mfc0 t0, CP0_PAGEGRAIN
or t0, (0x1 << 29)
mtc0 t0, CP0_PAGEGRAIN
-#ifdef CONFIG_LOONGSON3_ENHANCEMENT
/* Enable STFill Buffer */
+ mfc0 t0, CP0_PRID
+ andi t0, (PRID_IMP_MASK | PRID_REV_MASK)
+ slti t0, (PRID_IMP_LOONGSON_64 | PRID_REV_LOONGSON3A_R2)
+ bnez t0, 1f
mfc0 t0, CP0_CONFIG6
or t0, 0x100
mtc0 t0, CP0_CONFIG6
-#endif
+1:
_ehb
.set pop
#endif
@@ -52,12 +57,15 @@
mfc0 t0, CP0_PAGEGRAIN
or t0, (0x1 << 29)
mtc0 t0, CP0_PAGEGRAIN
-#ifdef CONFIG_LOONGSON3_ENHANCEMENT
/* Enable STFill Buffer */
+ mfc0 t0, CP0_PRID
+ andi t0, (PRID_IMP_MASK | PRID_REV_MASK)
+ slti t0, (PRID_IMP_LOONGSON_64 | PRID_REV_LOONGSON3A_R2)
+ bnez t0, 1f
mfc0 t0, CP0_CONFIG6
or t0, 0x100
mtc0 t0, CP0_CONFIG6
-#endif
+1:
_ehb
.set pop
#endif