mips: loongson64: remove unreachable(), fix loongson_poweroff().

biergaizi · paulburton · commit 8a96669d7789 · 2019-02-07T11:50:14.000-08:00
On my Yeeloong 8089, I noticed the machine fails to shutdown properly, and often, the function mach_prepare_reboot() is unexpectedly executed, thus the machine reboots instead. A wait loop is needed to ensure the system is in a well-defined state before going down. In commit 997e93d ("MIPS: Hang more efficiently on halt/powerdown/restart"), a general superset of the wait loop for all platforms is already provided, so we don't need to implement our own. This commit simply removes the unreachable() compiler marco after mach_prepare_reboot(), thus allowing the execution of machine_hang(). My test shows that the machine is now able to shutdown successfully. Please note that there are two different bugs preventing the machine from shutting down, another work-in-progress commit is needed to fix a lockup in cpufreq / i8259 driver, please read Reference, this commit does not fix that bug. Reference: https://lkml.org/lkml/2019/2/5/908 Signed-off-by: Yifeng Li <tomli@tomli.me> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org Cc: Huacai Chen <chenhc@lemote.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: Aaro Koskinen <aaro.koskinen@iki.fi> Cc: stable@vger.kernel.org # v4.17+
diff --git a/arch/mips/loongson64/common/reset.c b/arch/mips/loongson64/common/reset.c
@@ -59,7 +59,12 @@ static void loongson_poweroff(void)
 {
 #ifndef CONFIG_LEFI_FIRMWARE_INTERFACE
 	mach_prepare_shutdown();
-	unreachable();
+
+	/*
+	 * It needs a wait loop here, but mips/kernel/reset.c already calls
+	 * a generic delay loop, machine_hang(), so simply return.
+	 */
+	return;
 #else
 	void (*fw_poweroff)(void) = (void *)loongson_sysconf.poweroff_addr;
 
