From:   Huacai Chen <chenhc@lemote.com>
To:     Ralf Baechle <ralf@linux-mips.org>
Cc:     James Hogan <james.hogan@mips.com>,
        "Steven J . Hill" <Steven.Hill@cavium.com>,
        linux-mips@linux-mips.org, Fuxin Zhang <zhangfx@lemote.com>,
        Zhangjin Wu <wuzhangjin@gmail.com>,
        Huacai Chen <chenhc@lemote.com>
Subject: [PATCH V2 03/12] MIPS: Loongson-3: Enable Store Fill Buffer at runtime
Date:   Sat, 27 Jan 2018 11:12:23 +0800
Message-Id: <1517022752-3053-4-git-send-email-chenhc@lemote.com>
In-Reply-To: <1517022752-3053-1-git-send-email-chenhc@lemote.com>
References: <1517022752-3053-1-git-send-email-chenhc@lemote.com>
Original-Recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
Errors-to: linux-mips-bounce@linux-mips.org
Precedence: bulk

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).

Signed-off-by: Huacai Chen <chenhc@lemote.com>
---
 arch/mips/include/asm/io.h                                |  2 +-
 arch/mips/include/asm/mach-loongson64/kernel-entry-init.h | 14 ++++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 0cbf3af..5146efa 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -304,7 +304,7 @@ 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()		do { } while (0)
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..4b7f58a 100644
--- a/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h
+++ b/arch/mips/include/asm/mach-loongson64/kernel-entry-init.h
@@ -26,12 +26,15 @@
 	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, 0xffff
+	slti	t0, 0x6308
+	bnez	t0, 1f
 	mfc0	t0, CP0_CONFIG6
 	or	t0, 0x100
 	mtc0	t0, CP0_CONFIG6
-#endif
+1:
 	_ehb
 	.set	pop
 #endif
@@ -52,12 +55,15 @@
 	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, 0xffff
+	slti	t0, 0x6308
+	bnez	t0, 1f
 	mfc0	t0, CP0_CONFIG6
 	or	t0, 0x100
 	mtc0	t0, CP0_CONFIG6
-#endif
+1:
 	_ehb
 	.set	pop
 #endif
-- 
2.7.0