[PATCH net 1/1] net: stmmac: add aux timestamps fifo clearance wait

[Noor Azura Ahmad Tarmizi]

Add timeout polling wait for auxiliary timestamps snapshot FIFO clear bit
(ATSFC) to clear. This is to ensure no residue fifo value is being read
erroneously.

Cc: <stable at vger.kernel.org> # 5.10.x
Signed-off-by: Noor Azura Ahmad Tarmizi <noor.azura.ahmad.tarmizi at intel.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index fc06ddeac0d5..b4388ca8d211 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -210,7 +210,10 @@ static int stmmac_enable(struct ptp_clock_info *ptp,
 		}
 		writel(acr_value, ptpaddr + PTP_ACR);
 		mutex_unlock(&priv->aux_ts_lock);
-		ret = 0;
+		/* wait for auxts fifo clear to finish */
+		ret = readl_poll_timeout(ptpaddr + PTP_ACR, acr_value,
+					 !(acr_value & PTP_ACR_ATSFC),
+					 10, 10000);
 		break;
 
 	default:
-- 
2.17.1