linux-kernel - [PATCH 09/17] riscv: improve the default power off implementation

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Message-Id: <20190610221621.10938-10-hch@lst.de>
Date:   Tue, 11 Jun 2019 00:16:13 +0200
From:   Christoph Hellwig <hch@....de>
To:     Palmer Dabbelt <palmer@...ive.com>
Cc:     Damien Le Moal <damien.lemoal@....com>,
        linux-riscv@...ts.infradead.org, uclinux-dev@...inux.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 09/17] riscv: improve the default power off implementation

Only call the SBI code if we are not running in M mode, and if we didn't
do the SBI call, or it didn't succeed call wfi in a loop to at least
save some power.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/riscv/kernel/reset.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/reset.c b/arch/riscv/kernel/reset.c
index cfb6eb1d762d..17c810985ad0 100644
--- a/arch/riscv/kernel/reset.c
+++ b/arch/riscv/kernel/reset.c
@@ -8,8 +8,11 @@
 
 static void default_power_off(void)
 {
+#ifndef CONFIG_M_MODE
 	sbi_shutdown();
-	while (1);
+#endif
+	while (1)
+		wait_for_interrupt();
 }
 
 void (*pm_power_off)(void) = default_power_off;
-- 
2.20.1