[PATCH net-next v2 2/2] net: macb: Optimize reading HW timestamp

[Harini Katakam]

From: Harini Katakam <harini.katakam@xxxxxxxxxx>

The seconds input from BD (6 bits) just needs to be ORed with the
upper bits from timer in this function. Avoid addition operation
every single time. Seconds rollover handling is left untouched.

Signed-off-by: Harini Katakam <harini.katakam@xxxxxxxxxx>
Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxxxxx>
---
v2:
- Update HW timestamp logic to remove sec_rollover variable as per
Cladiu's comment
- Remove Richard Cochran's ACK on original patch as the patch changed

 drivers/net/ethernet/cadence/macb_ptp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_ptp.c b/drivers/net/ethernet/cadence/macb_ptp.c
index e6cb20aaa76a..f9db4501b995 100644
--- a/drivers/net/ethernet/cadence/macb_ptp.c
+++ b/drivers/net/ethernet/cadence/macb_ptp.c
@@ -258,6 +258,8 @@ static int gem_hw_timestamp(struct macb *bp, u32 dma_desc_ts_1,
 	 */
 	gem_tsu_get_time(&bp->ptp_clock_info, &tsu, NULL);
 
+	ts->tv_sec |= ((~GEM_DMA_SEC_MASK) & tsu.tv_sec);
+
 	/* If the top bit is set in the timestamp,
 	 * but not in 1588 timer, it has rolled over,
 	 * so subtract max size
@@ -266,8 +268,6 @@ static int gem_hw_timestamp(struct macb *bp, u32 dma_desc_ts_1,
 	    !(tsu.tv_sec & (GEM_DMA_SEC_TOP >> 1)))
 		ts->tv_sec -= GEM_DMA_SEC_TOP;
 
-	ts->tv_sec += ((~GEM_DMA_SEC_MASK) & tsu.tv_sec);
-
 	return 0;
 }
 
-- 
2.17.1