diff options
| author | Huacai Chen <chenhc@lemote.com> | 2018-09-05 17:33:01 +0800 |
|---|---|---|
| committer | Paul Burton <paul.burton@mips.com> | 2018-09-18 16:21:52 -0700 |
| commit | c824ad164760484f709daa1339df40a184f4170a (patch) | |
| tree | 9c824ca14aff39d91570f261a18a43f2603de7ec /arch/mips/include/asm/mach-loongson64 | |
| parent | 2794f688b2c336e0da85e9f91fed33febbd9f54a (diff) | |
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/include/asm/mach-loongson64')
| -rw-r--r-- | arch/mips/include/asm/mach-loongson64/kernel-entry-init.h | 16 |
1 files changed, 12 insertions, 4 deletions
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 |