MIPS: malta-time: Start GIC count before syncing to RTC

The sampling of the GIC counter on Malta after observing a rising edge
of the RTC update flag differs slightly between the first and second
sample, with the first sample also calling gic_start_count(). The two
samples should really be taken as similarly as possible to get the most
accurate figure, so move the gic_start_count() call before detecting the
rising edge.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13173/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/mti-malta/malta-time.c b/arch/mips/mti-malta/malta-time.c
index b7bf721..2539687 100644 (file)
--- a/arch/mips/mti-malta/malta-time.c
+++ b/arch/mips/mti-malta/malta-time.c
@@ -81,16 +81,16 @@ static void __init estimate_frequencies(void)
 
        local_irq_save(flags);
 
-       /* Start counter exactly on falling edge of update flag. */
+       if (gic_present)
+               gic_start_count();
+
+       /* Read counter exactly on falling edge of update flag. */
        while (CMOS_READ(RTC_REG_A) & RTC_UIP);
        while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
 
-       /* Initialize counters. */
        start = read_c0_count();
-       if (gic_present) {
-               gic_start_count();
+       if (gic_present)
                gicstart = gic_read_count();
-       }
 
        /* Read counter exactly on falling edge of update flag. */
        while (CMOS_READ(RTC_REG_A) & RTC_UIP);