linux-kernel - [PATCH] MIPS: Loongson64: Switch to SYNC

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Message-Id: <20240714-loongson64-cevt-r4k-v1-1-98afed7260aa@flygoat.com>
Date: Sun, 14 Jul 2024 10:41:05 +0800
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 Huacai Chen <chenhuacai@...nel.org>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: [PATCH] MIPS: Loongson64: Switch to SYNC_R4K

Nowadays SYNC_R4K is performing better than Loongson64's
custom sync mechanism.

Switch to SYNC_R4K to improve performance and reduce code
duplication.

Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
Last minute for 6.11 :-)
---
 arch/mips/Kconfig           |  1 +
 arch/mips/include/asm/smp.h |  1 -
 arch/mips/loongson64/smp.c  | 35 ++---------------------------------
 3 files changed, 3 insertions(+), 34 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1236ea122061..e163059dd4d3 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -478,6 +478,7 @@ config MACH_LOONGSON64
 	select BOARD_SCACHE
 	select CSRC_R4K
 	select CEVT_R4K
+	select SYNC_R4K
 	select FORCE_PCI
 	select ISA
 	select I8259
diff --git a/arch/mips/include/asm/smp.h b/arch/mips/include/asm/smp.h
index bc2c240f414b..2427d76f953f 100644
--- a/arch/mips/include/asm/smp.h
+++ b/arch/mips/include/asm/smp.h
@@ -50,7 +50,6 @@ extern int __cpu_logical_map[NR_CPUS];
 #define SMP_CALL_FUNCTION	0x2
 /* Octeon - Tell another core to flush its icache */
 #define SMP_ICACHE_FLUSH	0x4
-#define SMP_ASK_C0COUNT		0x8
 
 /* Mask of CPUs which are currently definitely operating coherently */
 extern cpumask_t cpu_coherent_mask;
diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
index 66d049cdcf14..147acd972a07 100644
--- a/arch/mips/loongson64/smp.c
+++ b/arch/mips/loongson64/smp.c
@@ -33,7 +33,6 @@ static void __iomem *ipi_clear0_regs[16];
 static void __iomem *ipi_status0_regs[16];
 static void __iomem *ipi_en0_regs[16];
 static void __iomem *ipi_mailbox_buf[16];
-static uint32_t core0_c0count[NR_CPUS];
 
 static u32 (*ipi_read_clear)(int cpu);
 static void (*ipi_write_action)(int cpu, u32 action);
@@ -382,11 +381,10 @@ loongson3_send_ipi_mask(const struct cpumask *mask, unsigned int action)
 		ipi_write_action(cpu_logical_map(i), (u32)action);
 }
 
-
 static irqreturn_t loongson3_ipi_interrupt(int irq, void *dev_id)
 {
-	int i, cpu = smp_processor_id();
-	unsigned int action, c0count;
+	int cpu = smp_processor_id();
+	unsigned int action;
 
 	action = ipi_read_clear(cpu);
 
@@ -399,26 +397,14 @@ static irqreturn_t loongson3_ipi_interrupt(int irq, void *dev_id)
 		irq_exit();
 	}
 
-	if (action & SMP_ASK_C0COUNT) {
-		BUG_ON(cpu != 0);
-		c0count = read_c0_count();
-		c0count = c0count ? c0count : 1;
-		for (i = 1; i < nr_cpu_ids; i++)
-			core0_c0count[i] = c0count;
-		nudge_writes(); /* Let others see the result ASAP */
-	}
-
 	return IRQ_HANDLED;
 }
 
-#define MAX_LOOPS 800
 /*
  * SMP init and finish on secondary CPUs
  */
 static void loongson3_init_secondary(void)
 {
-	int i;
-	uint32_t initcount;
 	unsigned int cpu = smp_processor_id();
 	unsigned int imask = STATUSF_IP7 | STATUSF_IP6 |
 			     STATUSF_IP3 | STATUSF_IP2;
@@ -432,23 +418,6 @@ static void loongson3_init_secondary(void)
 		     cpu_logical_map(cpu) % loongson_sysconf.cores_per_package);
 	cpu_data[cpu].package =
 		cpu_logical_map(cpu) / loongson_sysconf.cores_per_package;
-
-	i = 0;
-	core0_c0count[cpu] = 0;
-	loongson3_send_ipi_single(0, SMP_ASK_C0COUNT);
-	while (!core0_c0count[cpu]) {
-		i++;
-		cpu_relax();
-	}
-
-	if (i > MAX_LOOPS)
-		i = MAX_LOOPS;
-	if (cpu_data[cpu].package)
-		initcount = core0_c0count[cpu] + i;
-	else /* Local access is faster for loops */
-		initcount = core0_c0count[cpu] + i/2;
-
-	write_c0_count(initcount);
 }
 
 static void loongson3_smp_finish(void)

---
base-commit: 0b58e108042b0ed28a71cd7edf5175999955b233
change-id: 20240714-loongson64-cevt-r4k-eb74d4ad984c

Best regards,
-- 
Jiaxun Yang <jiaxun.yang@...goat.com>