Only restart auto-negotiation and write link timer if actually
necessary.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/net/ethernet/mediatek/mtk_sgmii.c | 24 +++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_sgmii.c b/drivers/net/ethernet/mediatek/mtk_sgmii.c
index d8184448cd5a..9c58006d1c33 100644
--- a/drivers/net/ethernet/mediatek/mtk_sgmii.c
+++ b/drivers/net/ethernet/mediatek/mtk_sgmii.c
@@ -38,20 +38,16 @@ static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 			  const unsigned long *advertising,
 			  bool permit_pause_to_mac)
 {
+	bool mode_changed = false, changed, use_an;
 	struct mtk_pcs *mpcs = pcs_to_mtk_pcs(pcs);
 	unsigned int rgc3, sgm_mode, bmcr;
 	int advertise, link_timer;
-	bool changed, use_an;
 
 	advertise = phylink_mii_c22_pcs_encode_advertisement(interface,
 							     advertising);
 	if (advertise < 0)
 		return advertise;
 
-	link_timer = phylink_get_link_timer_ns(interface);
-	if (link_timer < 0)
-		return link_timer;
-
 	/* Clearing IF_MODE_BIT0 switches the PCS to BASE-X mode, and
 	 * we assume that fixes it's speed at bitrate = line rate (in
 	 * other words, 1000Mbps or 2500Mbps).
@@ -77,8 +73,7 @@ static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 	}
 
 	if (use_an) {
-		/* FIXME: Do we need to set AN_RESTART here? */
-		bmcr = SGMII_AN_RESTART | SGMII_AN_ENABLE;
+		bmcr = SGMII_AN_ENABLE;
 	} else {
 		bmcr = 0;
 	}
@@ -106,16 +101,21 @@ static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 		regmap_update_bits(mpcs->regmap, mpcs->ana_rgc3,
 				   RG_PHY_SPEED_3_125G, rgc3);
 
+		/* Setup the link timer and QPHY power up inside SGMIISYS */
+		link_timer = phylink_get_link_timer_ns(interface);
+		if (link_timer < 0)
+			return link_timer;
+
+		regmap_write(mpcs->regmap, SGMSYS_PCS_LINK_TIMER, link_timer / 2 / 8);
+
 		mpcs->interface = interface;
+		mode_changed = true;
 	}
 
 	/* Update the advertisement, noting whether it has changed */
 	regmap_update_bits_check(mpcs->regmap, SGMSYS_PCS_ADVERTISE,
 				 SGMII_ADVERTISE, advertise, &changed);
 
-	/* Setup the link timer and QPHY power up inside SGMIISYS */
-	regmap_write(mpcs->regmap, SGMSYS_PCS_LINK_TIMER, link_timer / 2 / 8);
-
 	/* Update the sgmsys mode register */
 	regmap_update_bits(mpcs->regmap, SGMSYS_SGMII_MODE,
 			   SGMII_REMOTE_FAULT_DIS | SGMII_SPEED_DUPLEX_AN |
@@ -123,7 +123,7 @@ static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 
 	/* Update the BMCR */
 	regmap_update_bits(mpcs->regmap, SGMSYS_PCS_CONTROL_1,
-			   SGMII_AN_RESTART | SGMII_AN_ENABLE, bmcr);
+			   SGMII_AN_ENABLE, bmcr);
 
 	/* Release PHYA power down state
 	 * Only removing bit SGMII_PHYA_PWD isn't enough.
@@ -137,7 +137,7 @@ static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
 	usleep_range(50, 100);
 	regmap_write(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL, 0);
 
-	return changed;
+	return changed || mode_changed;
 }
 
 static void mtk_pcs_restart_an(struct phylink_pcs *pcs)
-- 
2.39.1

On Tue, Feb 07, 2023 at 02:21:25PM +0000, Daniel Golle wrote:
> @@ -106,16 +101,21 @@ static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
>  		regmap_update_bits(mpcs->regmap, mpcs->ana_rgc3,
>  				   RG_PHY_SPEED_3_125G, rgc3);
>  
> +		/* Setup the link timer and QPHY power up inside SGMIISYS */
> +		link_timer = phylink_get_link_timer_ns(interface);
> +		if (link_timer < 0)
> +			return link_timer;

I know I asked for this to be placed inside this if(), but I'd prefer it
if it were before any register state was touched, so if it returns an
error then no register state is affected by the pcs_config() call.

IIRC, we don't touch any state before the if(), so it should be a
matter of placing it as one of the first things in the if() block.

Thanks!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!