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authorLaurence Evans <levans@solarflare.com>2013-11-21 14:38:24 +0400
committerBen Hutchings <bhutchings@solarflare.com>2013-12-13 02:07:08 +0400
commitdfd8d581fbdce9f3b4777a7c59d28ca35ed194be (patch)
treee48f0e1fb90d2b0d57ecb99508b985ae2a3a4727 /drivers/net/ethernet
parent94cd60d09eba9e8de0522d416d867fb16858fccd (diff)
downloadlinux-dfd8d581fbdce9f3b4777a7c59d28ca35ed194be.tar.xz
sfc: Tidy up PTP synchronization code
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Diffstat (limited to 'drivers/net/ethernet')
-rw-r--r--drivers/net/ethernet/sfc/ptp.c44
1 files changed, 24 insertions, 20 deletions
diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 82d8e27e8a58..361d7cedd897 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -435,7 +435,6 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
MCDI_VAR_ARRAY_LEN(response_length,
PTP_OUT_SYNCHRONIZE_TIMESET);
unsigned i;
- unsigned total;
unsigned ngood = 0;
unsigned last_good = 0;
struct efx_ptp_data *ptp = efx->ptp_data;
@@ -446,33 +445,38 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
if (number_readings == 0)
return -EAGAIN;
- /* Read the set of results and increment stats for any results that
- * appera to be erroneous.
+ /* Read the set of results and find the last good host-MC
+ * synchronization result. The MC times when it finishes reading the
+ * host time so the corrected window time should be fairly constant
+ * for a given platform.
*/
for (i = 0; i < number_readings; i++) {
+ s32 window, corrected;
+
efx_ptp_read_timeset(
MCDI_ARRAY_STRUCT_PTR(synch_buf,
PTP_OUT_SYNCHRONIZE_TIMESET, i),
&ptp->timeset[i]);
- }
- /* Find the last good host-MC synchronization result. The MC times
- * when it finishes reading the host time so the corrected window time
- * should be fairly constant for a given platform.
- */
- total = 0;
- for (i = 0; i < number_readings; i++)
- if (ptp->timeset[i].window > ptp->timeset[i].waitns) {
- unsigned win;
-
- win = ptp->timeset[i].window - ptp->timeset[i].waitns;
- if (win >= MIN_SYNCHRONISATION_NS &&
- win < MAX_SYNCHRONISATION_NS) {
- total += ptp->timeset[i].window;
- ngood++;
- last_good = i;
- }
+ window = ptp->timeset[i].window;
+ corrected = window - ptp->timeset[i].waitns;
+
+ /* We expect the uncorrected synchronization window to be at
+ * least as large as the interval between host start and end
+ * times. If it is smaller than this then this is mostly likely
+ * to be a consequence of the host's time being adjusted.
+ * Check that the corrected sync window is in a reasonable
+ * range. If it is out of range it is likely to be because an
+ * interrupt or other delay occurred between reading the system
+ * time and writing it to MC memory.
+ */
+ if (window >= SYNCHRONISATION_GRANULARITY_NS &&
+ corrected < MAX_SYNCHRONISATION_NS &&
+ corrected >= MIN_SYNCHRONISATION_NS) {
+ ngood++;
+ last_good = i;
}
+ }
if (ngood == 0) {
netif_warn(efx, drv, efx->net_dev,