[PATCH v5 net-next 07/13] net: enetc: remove ERR050089 workaround for i.MX95

Wei Fang
2024-10-24T07:09:24Z

From: Vladimir Oltean <vladimir.oltean@nxp.com>

The ERR050089 workaround causes performance degradation and potential
functional issues (e.g., RCU stalls) under certain workloads. Since
new SoCs like i.MX95 do not require this workaround, use a static key
to compile out enetc_lock_mdio() and enetc_unlock_mdio() at runtime,
improving performance and avoiding unnecessary logic.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
---
v5: no changes
---
.../net/ethernet/freescale/enetc/enetc_hw.h | 34 +++++++++++++------
.../ethernet/freescale/enetc/enetc_pci_mdio.c | 17 ++++++++++
2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc_hw.h b/drivers/net/ethernet/freescale/enetc/enetc_hw.h
index 1619943fb263..6a7b9b75d660 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_hw.h
+++ b/drivers/net/ethernet/freescale/enetc/enetc_hw.h
@@ -396,18 +396,22 @@ struct enetc_hw {
*/
extern rwlock_t enetc_mdio_lock;

+DECLARE_STATIC_KEY_FALSE(enetc_has_err050089);
+
/* use this locking primitive only on the fast datapath to
* group together multiple non-MDIO register accesses to
* minimize the overhead of the lock
*/
static inline void enetc_lock_mdio(void)
{
- read_lock(&enetc_mdio_lock);
+ if (static_branch_unlikely(&enetc_has_err050089))
+ read_lock(&enetc_mdio_lock);
}

static inline void enetc_unlock_mdio(void)
{
- read_unlock(&enetc_mdio_lock);
+ if (static_branch_unlikely(&enetc_has_err050089))
+ read_unlock(&enetc_mdio_lock);
}

/* use these accessors only on the fast datapath under
@@ -416,14 +420,16 @@ static inline void enetc_unlock_mdio(void)
*/
static inline u32 enetc_rd_reg_hot(void __iomem *reg)
{
- lockdep_assert_held(&enetc_mdio_lock);
+ if (static_branch_unlikely(&enetc_has_err050089))
+ lockdep_assert_held(&enetc_mdio_lock);

return ioread32(reg);
}

static inline void enetc_wr_reg_hot(void __iomem *reg, u32 val)
{
- lockdep_assert_held(&enetc_mdio_lock);
+ if (static_branch_unlikely(&enetc_has_err050089))
+ lockdep_assert_held(&enetc_mdio_lock);

iowrite32(val, reg);
}
@@ -452,9 +458,13 @@ static inline u32 _enetc_rd_mdio_reg_wa(void __iomem *reg)
unsigned long flags;
u32 val;

- write_lock_irqsave(&enetc_mdio_lock, flags);
- val = ioread32(reg);
- write_unlock_irqrestore(&enetc_mdio_lock, flags);
+ if (static_branch_unlikely(&enetc_has_err050089)) {
+ write_lock_irqsave(&enetc_mdio_lock, flags);
+ val = ioread32(reg);
+ write_unlock_irqrestore(&enetc_mdio_lock, flags);
+ } else {
+ val = ioread32(reg);
+ }

return val;
}
@@ -463,9 +473,13 @@ static inline void _enetc_wr_mdio_reg_wa(void __iomem *reg, u32 val)
{
unsigned long flags;

- write_lock_irqsave(&enetc_mdio_lock, flags);
- iowrite32(val, reg);
- write_unlock_irqrestore(&enetc_mdio_lock, flags);
+ if (static_branch_unlikely(&enetc_has_err050089)) {
+ write_lock_irqsave(&enetc_mdio_lock, flags);
+ iowrite32(val, reg);
+ write_unlock_irqrestore(&enetc_mdio_lock, flags);
+ } else {
+ iowrite32(val, reg);
+ }
}

#ifdef ioread64
diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pci_mdio.c b/drivers/net/ethernet/freescale/enetc/enetc_pci_mdio.c
index a1b595bd7993..2445e35a764a 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_pci_mdio.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_pci_mdio.c
@@ -9,6 +9,9 @@
#define ENETC_MDIO_BUS_NAME ENETC_MDIO_DEV_NAME " Bus"
#define ENETC_MDIO_DRV_NAME ENETC_MDIO_DEV_NAME " driver"

+DEFINE_STATIC_KEY_FALSE(enetc_has_err050089);
+EXPORT_SYMBOL_GPL(enetc_has_err050089);
+
static int enetc_pci_mdio_probe(struct pci_dev *pdev,
const struct pci_device_id *ent)
{
@@ -62,6 +65,12 @@ static int enetc_pci_mdio_probe(struct pci_dev *pdev,
goto err_pci_mem_reg;
}

+ if (pdev->vendor == PCI_VENDOR_ID_FREESCALE &&
+ pdev->device == ENETC_MDIO_DEV_ID) {
+ static_branch_inc(&enetc_has_err050089);
+ dev_info(&pdev->dev, "Enabled ERR050089 workaround\n");
+ }
+
err = of_mdiobus_register(bus, dev->of_node);
if (err)
goto err_mdiobus_reg;
@@ -88,6 +97,14 @@ static void enetc_pci_mdio_remove(struct pci_dev *pdev)
struct enetc_mdio_priv *mdio_priv;

mdiobus_unregister(bus);
+
+ if (pdev->vendor == PCI_VENDOR_ID_FREESCALE &&
+ pdev->device == ENETC_MDIO_DEV_ID) {
+ static_branch_dec(&enetc_has_err050089);
+ if (!static_key_enabled(&enetc_has_err050089.key))
+ dev_info(&pdev->dev, "Disabled ERR050089 workaround\n");
+ }
+
mdio_priv = bus->priv;
iounmap(mdio_priv->hw->port);
pci_release_region(pdev, 0);
--
2.34.1