net: stmmac: Only update the auto-discovered PTP clock features

Some DWMAC variants such as dwmac1000 don't support discovering the
number of output pps and auxiliary snapshots. Allow these parameters to
be defined in default ptp_clock_info, and let them be updated only when
the feature discovery yielded a result.

Reviewed-by: Daniel Machon <[email protected]>
Signed-off-by: Maxime Chevallier <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: minimaxwell

drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c

@@ -303,8 +303,14 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
 	if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate)
 		priv->plat->cdc_error_adj = (2 * NSEC_PER_SEC) / priv->plat->clk_ptp_rate;
 
-	priv->ptp_clock_ops.n_per_out = priv->dma_cap.pps_out_num;
-	priv->ptp_clock_ops.n_ext_ts = priv->dma_cap.aux_snapshot_n;
+	/* Update the ptp clock parameters based on feature discovery, when
+	 * available
+	 */
+	if (priv->dma_cap.pps_out_num)
+		priv->ptp_clock_ops.n_per_out = priv->dma_cap.pps_out_num;
+
+	if (priv->dma_cap.aux_snapshot_n)
+		priv->ptp_clock_ops.n_ext_ts = priv->dma_cap.aux_snapshot_n;
 
 	if (priv->plat->ptp_max_adj)
 		priv->ptp_clock_ops.max_adj = priv->plat->ptp_max_adj;