4.19-stable review patch. If anyone has any objections, please let me know.
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From: Yifeng Li tomli@tomli.me
commit 8a96669d77897ff3613157bf43f875739205d66d upstream.
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 997e93d4df16 ("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+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/mips/loongson64/common/reset.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- 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;