diff options
| author | Kurt Kanzenbach <kurt@linutronix.de> | 2021-11-22 12:19:31 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-11-23 20:11:05 -0800 |
| commit | c6d5f1933085f9a92ed5c256a859ab31c7a35f88 (patch) | |
| tree | 652bed7110baf5cc643b18ddd9194180453423bd /drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | |
| parent | 2106efda785b55a8957efed9a52dfa28ee0d7280 (diff) | |
net: stmmac: Calculate CDC error only once
The clock domain crossing error (CDC) is calculated at every fetch of Tx or Rx
timestamps. It includes a division. Especially on arm32 based systems it is
expensive. It also requires two conditionals in the hotpath.
Add a compensation value cache to struct plat_stmmacenet_data and subtract it
unconditionally in the RX/TX functions which spares the conditionals.
The value is initialized to 0 and if supported calculated in the PTP
initialization code.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20211122111931.135135-1-kurt@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c')
| -rw-r--r-- | drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c index 580cc035536b..e14c97c04317 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c @@ -309,6 +309,11 @@ void stmmac_ptp_register(struct stmmac_priv *priv) if (priv->plat->ptp_max_adj) stmmac_ptp_clock_ops.max_adj = priv->plat->ptp_max_adj; + /* Calculate the clock domain crossing (CDC) error if necessary */ + priv->plat->cdc_error_adj = 0; + if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate) + priv->plat->cdc_error_adj = (2 * NSEC_PER_SEC) / priv->plat->clk_ptp_rate; + stmmac_ptp_clock_ops.n_per_out = priv->dma_cap.pps_out_num; stmmac_ptp_clock_ops.n_ext_ts = priv->dma_cap.aux_snapshot_n; |