This is a note to let you know that I've just added the patch titled ARC: timer: rtc: implement read loop in "C" vs. inline asm to the 4.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arc-timer-rtc-implement-read-loop-in-c-vs.-inline-asm.patch and it can be found in the queue-4.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 922cc171998ac3dbe74d57011ef7ed57e9b0d7df Mon Sep 17 00:00:00 2001 From: Vineet Gupta <vgupta@xxxxxxxxxxxx> Date: Mon, 31 Oct 2016 14:09:52 -0700 Subject: ARC: timer: rtc: implement read loop in "C" vs. inline asm From: Vineet Gupta <vgupta@xxxxxxxxxxxx> commit 922cc171998ac3dbe74d57011ef7ed57e9b0d7df upstream. The current code doesn't even compile as somehow the inline assembly can't see the register names defined as ARC_RTC_* I'm pretty sure It worked when I first got it merged, but the tools were definitely different then. So better to write this in "C" anyways. Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arc/kernel/time.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) --- a/arch/arc/kernel/time.c +++ b/arch/arc/kernel/time.c @@ -152,14 +152,17 @@ static cycle_t arc_read_rtc(struct clock cycle_t full; } stamp; - - __asm__ __volatile( - "1: \n" - " lr %0, [AUX_RTC_LOW] \n" - " lr %1, [AUX_RTC_HIGH] \n" - " lr %2, [AUX_RTC_CTRL] \n" - " bbit0.nt %2, 31, 1b \n" - : "=r" (stamp.low), "=r" (stamp.high), "=r" (status)); + /* + * hardware has an internal state machine which tracks readout of + * low/high and updates the CTRL.status if + * - interrupt/exception taken between the two reads + * - high increments after low has been read + */ + do { + stamp.low = read_aux_reg(AUX_RTC_LOW); + stamp.high = read_aux_reg(AUX_RTC_HIGH); + status = read_aux_reg(AUX_RTC_CTRL); + } while (!(status & _BITUL(31))); return stamp.full; } Patches currently in stable-queue which might be from vgupta@xxxxxxxxxxxx are queue-4.8/arc-implement-arch-specific-dma_map_ops.mmap.patch queue-4.8/arc-timer-rtc-implement-read-loop-in-c-vs.-inline-asm.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html