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Date: Wed, 17 May 2023 15:12:29 +0100
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Jose Abreu <Jose.Abreu@...opsys.com>
Cc: Andrew Lunn <andrew@...n.ch>,
Heiner Kallweit <hkallweit1@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
netdev@...r.kernel.org
Subject: [PATCH RFC net-next 9/9] net: pcs: xpcs: avoid reading STAT1 more
than once
Avoid reading the STAT1 registers more than once while getting the PCS
state, as this register contains latching-low bits that are lost after
the first read.
Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
drivers/net/pcs/pcs-xpcs.c | 91 +++++++++++++++++++++-----------------
1 file changed, 50 insertions(+), 41 deletions(-)
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index c5fe944f48dd..00cbd522f59a 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -271,15 +271,12 @@ static int xpcs_soft_reset(struct dw_xpcs *xpcs,
})
static int xpcs_read_fault_c73(struct dw_xpcs *xpcs,
- struct phylink_link_state *state)
+ struct phylink_link_state *state,
+ u16 pcs_stat1)
{
int ret;
- ret = xpcs_read(xpcs, MDIO_MMD_PCS, MDIO_STAT1);
- if (ret < 0)
- return ret;
-
- if (ret & MDIO_STAT1_FAULT) {
+ if (pcs_stat1 & MDIO_STAT1_FAULT) {
xpcs_warn(xpcs, state, "Link fault condition detected!\n");
return -EFAULT;
}
@@ -321,21 +318,6 @@ static int xpcs_read_fault_c73(struct dw_xpcs *xpcs,
return 0;
}
-static int xpcs_read_link_c73(struct dw_xpcs *xpcs)
-{
- bool link = true;
- int ret;
-
- ret = xpcs_read(xpcs, MDIO_MMD_PCS, MDIO_STAT1);
- if (ret < 0)
- return ret;
-
- if (!(ret & MDIO_STAT1_LSTATUS))
- link = false;
-
- return link;
-}
-
static void xpcs_config_usxgmii(struct dw_xpcs *xpcs, int speed)
{
int ret, speed_sel;
@@ -462,15 +444,11 @@ static int xpcs_config_aneg_c73(struct dw_xpcs *xpcs,
static int xpcs_aneg_done_c73(struct dw_xpcs *xpcs,
struct phylink_link_state *state,
- const struct xpcs_compat *compat)
+ const struct xpcs_compat *compat, u16 an_stat1)
{
int ret;
- ret = xpcs_read(xpcs, MDIO_MMD_AN, MDIO_STAT1);
- if (ret < 0)
- return ret;
-
- if (ret & MDIO_AN_STAT1_COMPLETE) {
+ if (an_stat1 & MDIO_AN_STAT1_COMPLETE) {
ret = xpcs_read(xpcs, MDIO_MMD_AN, MDIO_AN_LPA);
if (ret < 0)
return ret;
@@ -488,16 +466,12 @@ static int xpcs_aneg_done_c73(struct dw_xpcs *xpcs,
}
static int xpcs_read_lpa_c73(struct dw_xpcs *xpcs,
- struct phylink_link_state *state)
+ struct phylink_link_state *state, u16 an_stat1)
{
u16 lpa[3];
int i, ret;
- ret = xpcs_read(xpcs, MDIO_MMD_AN, MDIO_STAT1);
- if (ret < 0)
- return ret;
-
- if (!(ret & MDIO_AN_STAT1_LPABLE)) {
+ if (!(an_stat1 & MDIO_AN_STAT1_LPABLE)) {
phylink_clear(state->lp_advertising, Autoneg);
return 0;
}
@@ -880,13 +854,25 @@ static int xpcs_get_state_c73(struct dw_xpcs *xpcs,
const struct xpcs_compat *compat)
{
bool an_enabled;
+ int pcs_stat1;
+ int an_stat1;
int ret;
+ /* The link status bit is latching-low, so it is important to
+ * avoid unnecessary re-reads of this register to avoid missing
+ * a link-down event.
+ */
+ pcs_stat1 = xpcs_read(xpcs, MDIO_MMD_PCS, MDIO_STAT1);
+ if (pcs_stat1 < 0) {
+ state->link = false;
+ return pcs_stat1;
+ }
+
/* Link needs to be read first ... */
- state->link = xpcs_read_link_c73(xpcs) > 0 ? 1 : 0;
+ state->link = !!(pcs_stat1 & MDIO_STAT1_LSTATUS);
/* ... and then we check the faults. */
- ret = xpcs_read_fault_c73(xpcs, state);
+ ret = xpcs_read_fault_c73(xpcs, state, pcs_stat1);
if (ret) {
ret = xpcs_soft_reset(xpcs, compat);
if (ret)
@@ -897,15 +883,38 @@ static int xpcs_get_state_c73(struct dw_xpcs *xpcs,
return xpcs_do_config(xpcs, state->interface, MLO_AN_INBAND, NULL);
}
+ /* There is no point doing anything else if the link is down. */
+ if (!state->link)
+ return 0;
+
an_enabled = linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
state->advertising);
- if (an_enabled && xpcs_aneg_done_c73(xpcs, state, compat)) {
- state->an_complete = true;
- xpcs_read_lpa_c73(xpcs, state);
+ if (an_enabled) {
+ /* The link status bit is latching-low, so it is important to
+ * avoid unnecessary re-reads of this register to avoid missing
+ * a link-down event.
+ */
+ an_stat1 = xpcs_read(xpcs, MDIO_MMD_AN, MDIO_STAT1);
+ if (an_stat1 < 0) {
+ state->link = false;
+ return an_stat1;
+ }
+
+ state->an_complete = xpcs_aneg_done_c73(xpcs, state, compat,
+ an_stat1);
+ if (!state->an_complete) {
+ state->link = false;
+ return 0;
+ }
+
+ ret = xpcs_read_lpa_c73(xpcs, state, an_stat1);
+ if (ret < 0) {
+ state->link = false;
+ return ret;
+ }
+
phylink_resolve_c73(state);
- } else if (an_enabled) {
- state->link = 0;
- } else if (state->link) {
+ } else {
xpcs_resolve_pma(xpcs, state);
}
--
2.30.2
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