2 files changed, 24 insertions, 38 deletions

diff --git a/include/linux/timex.h b/include/linux/timex.h
index 671609ee1a3d..ac808f13fa0e 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -69,10 +69,9 @@
  * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
  * respectively.
  */
-#define SHIFT_KG 6              /* phase factor (shift) */
-#define SHIFT_KF 16             /* PLL frequency factor (shift) */
-#define SHIFT_KH 2              /* FLL frequency factor (shift) */
-#define MAXTC 6                 /* maximum time constant (shift) */
+#define SHIFT_PLL       4       /* PLL frequency factor (shift) */
+#define SHIFT_FLL       2       /* FLL frequency factor (shift) */
+#define MAXTC           10      /* maximum time constant (shift) */
 
 /*
  * The SHIFT_SCALE define establishes the decimal point of the time_phase
@@ -97,8 +96,8 @@
 #define MAXPHASE 512000L        /* max phase error (us) */
 #define MAXFREQ (512L << SHIFT_USEC)  /* max frequency error (ppm) */
 #define MAXFREQ_NSEC (512000L << SHIFT_NSEC) /* max frequency error (ppb) */
-#define MINSEC 16L              /* min interval between updates (s) */
-#define MAXSEC 1200L            /* max interval between updates (s) */
+#define MINSEC 256              /* min interval between updates (s) */
+#define MAXSEC 2048             /* max interval between updates (s) */
 #define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
 
 /*
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 9137b54613e0..1ab5e9d7fa50 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -145,18 +145,11 @@ void second_overflow(void)
         }
 
         /*
-         * Compute the phase adjustment for the next second. In PLL mode, the
-         * offset is reduced by a fixed factor times the time constant. In FLL
-         * mode the offset is used directly. In either mode, the maximum phase
-         * adjustment for each second is clamped so as to spread the adjustment
-         * over not more than the number of seconds between updates.
+         * Compute the phase adjustment for the next second. The offset is
+         * reduced by a fixed factor times the time constant.
          */
         tick_length = tick_length_base;
-        time_adj = time_offset;
-        if (!(time_status & STA_FLL))
-                time_adj = shift_right(time_adj, SHIFT_KG + time_constant);
-        time_adj = min(time_adj, -((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
-        time_adj = max(time_adj, ((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
+        time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
         time_offset -= time_adj;
         tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
 
@@ -200,7 +193,7 @@ void __attribute__ ((weak)) notify_arch_cmos_timer(void)
 int do_adjtimex(struct timex *txc)
 {
         long ltemp, mtemp, save_adjust;
-        s64 freq_adj;
+        s64 freq_adj, temp64;
         int result;
 
         /* In order to modify anything, you gotta be super-user! */
@@ -270,7 +263,7 @@ int do_adjtimex(struct timex *txc)
                     result = -EINVAL;
                     goto leave;
                 }
-                time_constant = txc->constant;
+                time_constant = min(txc->constant + 4, (long)MAXTC);
             }
 
             if (txc->modes & ADJ_OFFSET) {      /* values checked earlier */
@@ -298,26 +291,20 @@ int do_adjtimex(struct timex *txc)
                         time_reftime = xtime.tv_sec;
                     mtemp = xtime.tv_sec - time_reftime;
                     time_reftime = xtime.tv_sec;
-                    freq_adj = 0;
-                    if (time_status & STA_FLL) {
-                        if (mtemp >= MINSEC) {
-                            freq_adj = (s64)time_offset << (SHIFT_NSEC - SHIFT_KH);
-                            if (time_offset < 0) {
-                                freq_adj = -freq_adj;
-                                do_div(freq_adj, mtemp);
-                                freq_adj = -freq_adj;
-                            } else
-                                do_div(freq_adj, mtemp);
-                        } else /* calibration interval too short (p. 12) */
-                                result = TIME_ERROR;
-                    } else {    /* PLL mode */
-                        if (mtemp < MAXSEC) {
-                            freq_adj = (s64)ltemp * mtemp;
-                            freq_adj = shift_right(freq_adj,(time_constant +
-                                                       time_constant +
-                                                       SHIFT_KF - SHIFT_NSEC));
-                        } else /* calibration interval too long (p. 12) */
-                                result = TIME_ERROR;
+
+                    freq_adj = (s64)time_offset * mtemp;
+                    freq_adj = shift_right(freq_adj, time_constant * 2 +
+                                           (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
+                    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
+                        temp64 = (s64)time_offset << (SHIFT_NSEC - SHIFT_FLL);
+                        if (time_offset < 0) {
+                            temp64 = -temp64;
+                            do_div(temp64, mtemp);
+                            freq_adj -= temp64;
+                        } else {
+                            do_div(temp64, mtemp);
+                            freq_adj += temp64;
+                        }
                     }
                     freq_adj += time_freq;
                     freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);