2021-10-05 03:42:56

by Wong Vee Khee

Subject: [PATCH net v4 1/1] net: pcs: xpcs: fix incorrect CL37 AN sequence

According to Synopsys DesignWare Cores Ethernet PCS databook, it is
required to disable Clause 37 auto-negotiation by programming bit-12
(AN_ENABLE) to 0 if it is already enabled, before programming various
fields of VR_MII_AN_CTRL registers.

After all these programming are done, it is then required to enable
Clause 37 auto-negotiation by programming bit-12 (AN_ENABLE) to 1.

Fixes: b97b5331b8ab ("net: pcs: add C37 SGMII AN support for intel mGbE controller")
Cc: Vladimir Oltean <[email protected]>
Signed-off-by: Wong Vee Khee <[email protected]>
---
v3 -> v4:
- Removed redunctant 'changed' variable.
v2 -> v3:
- Added error handling after xpcs_write().
- Added 'changed' flag.
- Added fixes tag.
v1 -> v2:
- Removed use of xpcs_modify() helper function.
- Add conditional check on inband auto-negotiation.
---
drivers/net/pcs/pcs-xpcs.c | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index fb0a83dc09ac..a3e806cfa684 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -697,14 +697,17 @@ EXPORT_SYMBOL_GPL(xpcs_config_eee);

static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs, unsigned int mode)
{
- int ret;
+ int ret, mdio_ctrl;

/* For AN for C37 SGMII mode, the settings are :-
- * 1) VR_MII_AN_CTRL Bit(2:1)[PCS_MODE] = 10b (SGMII AN)
- * 2) VR_MII_AN_CTRL Bit(3) [TX_CONFIG] = 0b (MAC side SGMII)
+ * 1) VR_MII_MMD_CTRL Bit(12) [AN_ENABLE] = 0b (Disable SGMII AN in case
+ it is already enabled)
+ * 2) VR_MII_AN_CTRL Bit(2:1)[PCS_MODE] = 10b (SGMII AN)
+ * 3) VR_MII_AN_CTRL Bit(3) [TX_CONFIG] = 0b (MAC side SGMII)
* DW xPCS used with DW EQoS MAC is always MAC side SGMII.
- * 3) VR_MII_DIG_CTRL1 Bit(9) [MAC_AUTO_SW] = 1b (Automatic
+ * 4) VR_MII_DIG_CTRL1 Bit(9) [MAC_AUTO_SW] = 1b (Automatic
* speed/duplex mode change by HW after SGMII AN complete)
+ * 5) VR_MII_MMD_CTRL Bit(12) [AN_ENABLE] = 1b (Enable SGMII AN)
*
* Note: Since it is MAC side SGMII, there is no need to set
* SR_MII_AN_ADV. MAC side SGMII receives AN Tx Config from
@@ -712,6 +715,17 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs, unsigned int mode)
* between PHY and Link Partner. There is also no need to
* trigger AN restart for MAC-side SGMII.
*/
+ mdio_ctrl = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL);
+ if (mdio_ctrl < 0)
+ return mdio_ctrl;
+
+ if (mdio_ctrl & AN_CL37_EN) {
+ ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL,
+ mdio_ctrl & ~AN_CL37_EN);
+ if (ret < 0)
+ return ret;
+ }
+
ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_AN_CTRL);
if (ret < 0)
return ret;
@@ -736,7 +750,15 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs, unsigned int mode)
else
ret &= ~DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;

- return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
+ ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
+ if (ret < 0)
+ return ret;
+
+ if (phylink_autoneg_inband(mode))
+ ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL,
+ mdio_ctrl | AN_CL37_EN);
+
+ return ret;
}

static int xpcs_config_2500basex(struct dw_xpcs *xpcs)
--
2.25.1

2021-10-05 12:10:22

by Vladimir Oltean

Subject: Re: [PATCH net v4 1/1] net: pcs: xpcs: fix incorrect CL37 AN sequence

On Tue, Oct 05, 2021 at 11:45:21AM +0800, Wong Vee Khee wrote:
> According to Synopsys DesignWare Cores Ethernet PCS databook, it is
> required to disable Clause 37 auto-negotiation by programming bit-12
> (AN_ENABLE) to 0 if it is already enabled, before programming various
> fields of VR_MII_AN_CTRL registers.
>
> After all these programming are done, it is then required to enable
> Clause 37 auto-negotiation by programming bit-12 (AN_ENABLE) to 1.
>
> Fixes: b97b5331b8ab ("net: pcs: add C37 SGMII AN support for intel mGbE controller")
> Cc: Vladimir Oltean <[email protected]>
> Signed-off-by: Wong Vee Khee <[email protected]>
> ---

Reviewed-by: Vladimir Oltean <[email protected]>
Tested-by: Vladimir Oltean <[email protected]>

> v3 -> v4:
> - Removed redunctant 'changed' variable.

s/redunctant/redundant/

> v2 -> v3:
> - Added error handling after xpcs_write().
> - Added 'changed' flag.
> - Added fixes tag.
> v1 -> v2:
> - Removed use of xpcs_modify() helper function.
> - Add conditional check on inband auto-negotiation.
> ---