* [PATCH net-next 1/2] net: pcs: xpcs: re-order xpcs_pre_config() to update after the reset
2026-10-14 22:30 [PATCH net-next 0/2] net: pcs: xpcs: fix operating mode selection Alex Elder
@ 2026-10-14 22:30 ` Alex Elder
2026-10-14 22:30 ` [PATCH net-next 2/2] net: pcs: xpcs: select operating mode for 10G-baseR capable PCS Alex Elder
1 sibling, 0 replies; 3+ messages in thread
From: Alex Elder @ 2026-10-14 22:30 UTC (permalink / raw)
To: andrew, hkallweit1, linux, davem, edumazet, kuba, pabeni
Cc: Daniel Thompson, netdev, linux-kernel
From: Daniel Thompson <daniel@riscstar.com>
Currently, on Wangxun platforms, the XPCS is configured during the call
to xpcs_switch_interface_mode() and, if the need_reset flag is set, the
XPCS is reset and the configuration will be lost. This is harmless at
present because need_reset will never actually be set on these platforms.
Nevertheless having xpcs_switch_interface_mode() on the wrong side of
the reset is an obstacle for future changes where wiping out programmed
configuration with a reset could be harmful.
Reorder xpcs_pre_config() so the reset can happen before we switch
interface mode. To make this work we have to hoist the special case
logic for SGMII into the parent function.
Signed-off-by: Daniel Thompson <daniel@riscstar.com>
Co-developed-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Alex Elder <elder@riscstar.com>
---
drivers/net/pcs/pcs-xpcs.c | 59 ++++++++++++++++++++------------------
1 file changed, 31 insertions(+), 28 deletions(-)
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index b415b93d77c15..49abf5ea6f5cc 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -705,46 +705,49 @@ static void xpcs_get_interfaces(struct dw_xpcs *xpcs, unsigned long *interfaces)
static int xpcs_switch_interface_mode(struct dw_xpcs *xpcs,
phy_interface_t interface)
{
- int ret = 0;
+ /* Wangxun provides a full alternative implementation to handle quirks */
+ if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID)
+ return txgbe_xpcs_switch_mode(xpcs, interface);
- if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
- ret = txgbe_xpcs_switch_mode(xpcs, interface);
- } else if (xpcs->interface != interface) {
- if (interface == PHY_INTERFACE_MODE_SGMII)
- xpcs->need_reset = true;
- xpcs->interface = interface;
- }
+ xpcs->interface = interface;
- return ret;
+ return 0;
}
static void xpcs_pre_config(struct phylink_pcs *pcs, phy_interface_t interface)
{
struct dw_xpcs *xpcs = phylink_pcs_to_xpcs(pcs);
+ struct device *dev = &xpcs->mdiodev->dev;
const struct dw_xpcs_compat *compat;
+ bool force_reset;
int ret;
+ /*
+ * According to the XPCS datasheet, a soft reset is required to initiate
+ * Clause 37 auto-negotiation when the XPCS switches interface modes.
+ */
+ force_reset = interface == PHY_INTERFACE_MODE_SGMII;
+
+ if (force_reset || xpcs->need_reset) {
+ compat = xpcs_find_compat(xpcs, interface);
+ if (!compat) {
+ dev_err(dev, "unsupported interface %s\n",
+ phy_modes(interface));
+ return;
+ }
+
+ ret = xpcs_soft_reset(xpcs, compat);
+ if (ret) {
+ dev_err(dev, "soft reset failed: %pe\n", ERR_PTR(ret));
+ return;
+ }
+
+ xpcs->need_reset = false;
+ }
+
ret = xpcs_switch_interface_mode(xpcs, interface);
if (ret)
- dev_err(&xpcs->mdiodev->dev, "switch interface failed: %pe\n",
- ERR_PTR(ret));
-
- if (!xpcs->need_reset)
- return;
-
- compat = xpcs_find_compat(xpcs, interface);
- if (!compat) {
- dev_err(&xpcs->mdiodev->dev, "unsupported interface %s\n",
- phy_modes(interface));
- return;
- }
-
- ret = xpcs_soft_reset(xpcs, compat);
- if (ret)
- dev_err(&xpcs->mdiodev->dev, "soft reset failed: %pe\n",
- ERR_PTR(ret));
-
- xpcs->need_reset = false;
+ dev_err(dev, "switch interface failed: %pe\n", ERR_PTR(ret));
}
static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs,
--
2.53.0
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH net-next 2/2] net: pcs: xpcs: select operating mode for 10G-baseR capable PCS
2026-10-14 22:30 [PATCH net-next 0/2] net: pcs: xpcs: fix operating mode selection Alex Elder
2026-10-14 22:30 ` [PATCH net-next 1/2] net: pcs: xpcs: re-order xpcs_pre_config() to update after the reset Alex Elder
@ 2026-10-14 22:30 ` Alex Elder
1 sibling, 0 replies; 3+ messages in thread
From: Alex Elder @ 2026-10-14 22:30 UTC (permalink / raw)
To: andrew, hkallweit1, linux, davem, edumazet, kuba, pabeni
Cc: Daniel Thompson, netdev, linux-kernel
From: Daniel Thompson <daniel@riscstar.com>
Currently the XPCS found on Toshiba TC9564 is unable to operate at
2500base-X and slower with a PHY connected using SGMII/2500base-X
(in our case a Qualcomm QCA8081).
The problem arises because this XPCS supports 10Gbase-R. That means
that the reset value of SR_XS_PCS_CTRL2:PCS_TYPE_SEL (0) is valid and
this suppresses the modal switching based on bit 13 of SR_PMA_CTRL1
or SR_XS_PCS_CTRL1.
A fix for this behaviour is implemented by txgbe_xpcs_switch_mode()
as part of the quirks for WangXun devices.
Rather than introduce another quirk for TC9564 let's attempt so solve
this generically by setting SR_XS_PCS_CTRL2:PCS_TYPE_SEL to a reserved
value when we detect the right combination of phy interface and XPCS
feature support.
The generic strategy adopted requires the default value of PCS_TYPE_SEL
to be 0 on devices that support 10Gbase-R. Based on TC9564 documentation
and the logic already implemented for WangXun I believe this is likely
to be the case for currently supported XPCS devices. Sadly I don't have
access to generic XPCS docs to confirm. However I think the benefits
of avoiding a cargo culted quirk outweighs the risk of regression.
Signed-off-by: Daniel Thompson <daniel@riscstar.com>
Co-developed-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Alex Elder <elder@riscstar.com>
---
drivers/net/pcs/pcs-xpcs.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 49abf5ea6f5cc..5316cf9c31f19 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -705,10 +705,47 @@ static void xpcs_get_interfaces(struct dw_xpcs *xpcs, unsigned long *interfaces)
static int xpcs_switch_interface_mode(struct dw_xpcs *xpcs,
phy_interface_t interface)
{
+ int mdio_stat2, ret;
+
/* Wangxun provides a full alternative implementation to handle quirks */
if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID)
return txgbe_xpcs_switch_mode(xpcs, interface);
+ mdio_stat2 = xpcs_read(xpcs, MDIO_MMD_PCS, MDIO_STAT2);
+ if (mdio_stat2 < 0)
+ return mdio_stat2;
+
+ /*
+ * If this XPCS supports 10Gbase-R then that will be the default
+ * operating mode. There are several interface modes where this default
+ * is unhelpful. Change the operating mode for interfaces were we know
+ * the default is wrong, and restore the default otherwise.
+ */
+ if (mdio_stat2 & MDIO_PCS_STAT2_10GBR) {
+ switch (interface) {
+ case PHY_INTERFACE_MODE_SGMII:
+ case PHY_INTERFACE_MODE_1000BASEX:
+ case PHY_INTERFACE_MODE_2500BASEX:
+ /*
+ * Why are we writing MDIO_PCS_CTRL2_TYPE + 1? We want
+ * the modal behaviour that comes when we pick a
+ * reserved value. XPCS allocates extra bits to this
+ * field and allocates values from 15 down so
+ * MDIO_PCS_CTRL2_TYPE + 1 is the value likely to be
+ * allocated last (and hopefully never).
+ */
+ ret = xpcs_write(xpcs, MDIO_MMD_PCS, MDIO_CTRL2,
+ MDIO_PCS_CTRL2_TYPE + 1);
+ break;
+ default:
+ ret = xpcs_write(xpcs, MDIO_MMD_PCS, MDIO_CTRL2,
+ MDIO_PCS_CTRL2_10GBR);
+ break;
+ }
+ if (ret < 0)
+ return ret;
+ }
+
xpcs->interface = interface;
return 0;
--
2.53.0
^ permalink raw reply [flat|nested] 3+ messages in thread