From: Noor Azura Ahmad Tarmizi <noor.azura.ahmad.tarmizi@xxxxxxxxx> commit ae9dcb91c6069e20b3b9505d79cbc89fd6e086f5 upstream. 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. Fixes: f4da56529da6 ("net: stmmac: Add support for external trigger timestamping") Cc: <stable@xxxxxxxxxxxxxxx> # 5.10.x Signed-off-by: Noor Azura Ahmad Tarmizi <noor.azura.ahmad.tarmizi@xxxxxxxxx> Link: https://lore.kernel.org/r/20230111050200.2130-1-noor.azura.ahmad.tarmizi@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c @@ -229,7 +229,10 @@ static int stmmac_enable(struct ptp_cloc } 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: