From: Huacai Chen Date: Wed, 5 Sep 2018 09:33:01 +0000 (+0800) Subject: MIPS: Loongson-3: Enable Store Fill Buffer at runtime X-Git-Tag: v5.15~7722^2~35 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c824ad164760484f709daa1339df40a184f4170a;p=platform%2Fkernel%2Flinux-starfive.git 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 Signed-off-by: Paul Burton Patchwork: https://patchwork.linux-mips.org/patch/20426/ Cc: Ralf Baechle Cc: James Hogan Cc: linux-mips@linux-mips.org Cc: Fuxin Zhang Cc: Zhangjin Wu Cc: Huacai Chen --- diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h index 44f766b..eb357c9 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 3127391..cbac603 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 + /* * 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