5.15-stable review patch. If anyone has any objections, please let me know.
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From: Rohan G Thomas rohan.g.thomas@altera.com
[ Upstream commit deb105f49879dd50d595f7f55207d6e74dec34e6 ]
The 88e1510 PHY has an erratum where the phy downshift counter is not cleared after phy being suspended(BMCR_PDOWN set) and then later resumed(BMCR_PDOWN cleared). This can cause the gigabit link to intermittently downshift to a lower speed.
Disabling and re-enabling the downshift feature clears the counter, allowing the PHY to retry gigabit link negotiation up to the programmed retry count times before downshifting. This behavior has been observed on copper links.
Signed-off-by: Rohan G Thomas rohan.g.thomas@altera.com Reviewed-by: Matthew Gerlach matthew.gerlach@altera.com Reviewed-by: Andrew Lunn andrew@lunn.ch Link: https://patch.msgid.link/20250906-marvell_fix-v2-1-f6efb286937f@altera.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/phy/marvell.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c index 87975b843d276..4557bb2f68219 100644 --- a/drivers/net/phy/marvell.c +++ b/drivers/net/phy/marvell.c @@ -1753,6 +1753,43 @@ static int marvell_resume(struct phy_device *phydev) return err; }
+/* m88e1510_resume + * + * The 88e1510 PHY has an erratum where the phy downshift counter is not cleared + * after phy being suspended(BMCR_PDOWN set) and then later resumed(BMCR_PDOWN + * cleared). This can cause the link to intermittently downshift to a lower speed. + * + * Disabling and re-enabling the downshift feature clears the counter, allowing + * the PHY to retry gigabit link negotiation up to the programmed retry count + * before downshifting. This behavior has been observed on copper links. + */ +static int m88e1510_resume(struct phy_device *phydev) +{ + int err; + u8 cnt = 0; + + err = marvell_resume(phydev); + if (err < 0) + return err; + + /* read downshift counter value */ + err = m88e1011_get_downshift(phydev, &cnt); + if (err < 0) + return err; + + if (cnt) { + /* downshift disabled */ + err = m88e1011_set_downshift(phydev, 0); + if (err < 0) + return err; + + /* downshift enabled, with previous counter value */ + err = m88e1011_set_downshift(phydev, cnt); + } + + return err; +} + static int marvell_aneg_done(struct phy_device *phydev) { int retval = phy_read(phydev, MII_M1011_PHY_STATUS); @@ -3134,7 +3171,7 @@ static struct phy_driver marvell_drivers[] = { .handle_interrupt = marvell_handle_interrupt, .get_wol = m88e1318_get_wol, .set_wol = m88e1318_set_wol, - .resume = marvell_resume, + .resume = m88e1510_resume, .suspend = marvell_suspend, .read_page = marvell_read_page, .write_page = marvell_write_page,