Linux-libre 4.5-gnu

1 files changed, 19 insertions, 36 deletions

diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c
index 30d806ce0..c41c364b9 100644
--- a/arch/arc/kernel/mcip.c
+++ b/arch/arc/kernel/mcip.c
@@ -15,6 +15,7 @@
 #include <asm/mcip.h>
 #include <asm/setup.h>
 
+#define IPI_IRQ		19
 #define SOFTIRQ_IRQ	21
 
 static char smp_cpuinfo_buf[128];
@@ -39,39 +40,26 @@ static void mcip_ipi_send(int cpu)
 		return;
 	}
 
+	raw_spin_lock_irqsave(&mcip_lock, flags);
+
 	/*
-	 * NOTE: We must spin here if the other cpu hasn't yet
-	 * serviced a previous message. This can burn lots
-	 * of time, but we MUST follows this protocol or
-	 * ipi messages can be lost!!!
-	 * Also, we must release the lock in this loop because
-	 * the other side may get to this same loop and not
-	 * be able to ack -- thus causing deadlock.
+	 * If receiver already has a pending interrupt, elide sending this one.
+	 * Linux cross core calling works well with concurrent IPIs
+	 * coalesced into one
+	 * see arch/arc/kernel/smp.c: ipi_send_msg_one()
 	 */
+	__mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
+	ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
+	if (!ipi_was_pending)
+		__mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);
 
-	do {
-		raw_spin_lock_irqsave(&mcip_lock, flags);
-		__mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
-		ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
-		if (ipi_was_pending == 0)
-			break; /* break out but keep lock */
-		raw_spin_unlock_irqrestore(&mcip_lock, flags);
-	} while (1);
-
-	__mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);
 	raw_spin_unlock_irqrestore(&mcip_lock, flags);
-
-#ifdef CONFIG_ARC_IPI_DBG
-	if (ipi_was_pending)
-		pr_info("IPI ACK delayed from cpu %d\n", cpu);
-#endif
 }
 
 static void mcip_ipi_clear(int irq)
 {
 	unsigned int cpu, c;
 	unsigned long flags;
-	unsigned int __maybe_unused copy;
 
 	if (unlikely(irq == SOFTIRQ_IRQ)) {
 		arc_softirq_clear(irq);
@@ -83,7 +71,7 @@ static void mcip_ipi_clear(int irq)
 	/* Who sent the IPI */
 	__mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0);
 
-	copy = cpu = read_aux_reg(ARC_REG_MCIP_READBACK);	/* 1,2,4,8... */
+	cpu = read_aux_reg(ARC_REG_MCIP_READBACK);	/* 1,2,4,8... */
 
 	/*
 	 * In rare case, multiple concurrent IPIs sent to same target can
@@ -97,12 +85,6 @@ static void mcip_ipi_clear(int irq)
 	} while (cpu);
 
 	raw_spin_unlock_irqrestore(&mcip_lock, flags);
-
-#ifdef CONFIG_ARC_IPI_DBG
-	if (c != __ffs(copy))
-		pr_info("IPIs from %x coalesced to %x\n",
-			copy, raw_smp_processor_id());
-#endif
 }
 
 static void mcip_probe_n_setup(void)
@@ -111,13 +93,13 @@ static void mcip_probe_n_setup(void)
 #ifdef CONFIG_CPU_BIG_ENDIAN
 		unsigned int pad3:8,
 			     idu:1, llm:1, num_cores:6,
-			     iocoh:1,  grtc:1, dbg:1, pad2:1,
+			     iocoh:1,  gfrc:1, dbg:1, pad2:1,
 			     msg:1, sem:1, ipi:1, pad:1,
 			     ver:8;
 #else
 		unsigned int ver:8,
 			     pad:1, ipi:1, sem:1, msg:1,
-			     pad2:1, dbg:1, grtc:1, iocoh:1,
+			     pad2:1, dbg:1, gfrc:1, iocoh:1,
 			     num_cores:6, llm:1, idu:1,
 			     pad3:8;
 #endif
@@ -126,12 +108,13 @@ static void mcip_probe_n_setup(void)
 	READ_BCR(ARC_REG_MCIP_BCR, mp);
 
 	sprintf(smp_cpuinfo_buf,
-		"Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s\n",
+		"Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s%s\n",
 		mp.ver, mp.num_cores,
 		IS_AVAIL1(mp.ipi, "IPI "),
 		IS_AVAIL1(mp.idu, "IDU "),
+		IS_AVAIL1(mp.llm, "LLM "),
 		IS_AVAIL1(mp.dbg, "DEBUG "),
-		IS_AVAIL1(mp.grtc, "GRTC"));
+		IS_AVAIL1(mp.gfrc, "GFRC"));
 
 	idu_detected = mp.idu;
 
@@ -140,8 +123,8 @@ static void mcip_probe_n_setup(void)
 		__mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf);
 	}
 
-	if (IS_ENABLED(CONFIG_ARC_HAS_GRTC) && !mp.grtc)
-		panic("kernel trying to use non-existent GRTC\n");
+	if (IS_ENABLED(CONFIG_ARC_HAS_GFRC) && !mp.gfrc)
+		panic("kernel trying to use non-existent GFRC\n");
 }
 
 struct plat_smp_ops plat_smp_ops = {