Messages in this thread Patch in this message | | | Subject | Re: [PATCH net-next v2 4/6] net: mdio: scan bus based on bus capabilities for C22 and C45 | From | Klaus Kudielka <> | Date | Wed, 08 Mar 2023 19:34:40 +0100 |
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On Tue, 2023-03-07 at 21:35 +0100, Andrew Lunn wrote: > > Summary: Still 4 calls to mdio_bus_scan_c22, but also *2* calls to mdio_bus_scan_c45, approx. 190*100 reads by the switch driver > > Those calls to mdio_bus_scan_c45 are caused by 743a19e38d02 net: dsa: > mv88e6xxx: Separate C22 and C45 transactions.
Well, yes and no. I understand orion mdio is MDIOBUS_NO_CAP and therefore the c45 scan is *not* called until 1a136ca2e0 net: mdio: scan bus based on bus capabilities for C22 and C45. Which is the behaviour I see. (I needed a close look at the conditions in the if statements that were removed then)
> The only part of a c45 scan which is not linear is > mv88e6xxx_g2_smi_phy_wait() which is implemented by > mv88e6xxx_wait_mask(). That loops reading a register waiting for a bit > to change. Maybe print out the value of i, and see if it is looping > more times for C45 than C22?
Here the debug code
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 0a5d6c7bb1..23816cad41 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -90,6 +90,7 @@ int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg, u16 data; int err; int i; + static unsigned wait_count = 0, loop_count = 0; /* There's no bus specific operation to wait for a mask. Even * if the initial poll takes longer than 50ms, always do at @@ -100,8 +101,13 @@ int mv88e6xxx_wait_mask(struct mv88e6xxx_chip *chip, int addr, int reg, if (err) return err; - if ((data & mask) == val) + if ((data & mask) == val) { + wait_count++; + loop_count += i; + if (wait_count % 10 == 0) + dev_warn(chip->dev, "wait_count %u, loop_count %u\n", wait_count, loop_count); return 0; + } if (i < 2) cpu_relax(); diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 5b2f48c09a..19fde21cae 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -569,6 +569,7 @@ static int mdiobus_scan_bus_c22(struct mii_bus *bus) { int i; + dev_warn(&bus->dev, "*** mdiobus_scan_bus_c22 call ***\n"); for (i = 0; i < PHY_MAX_ADDR; i++) { if ((bus->phy_mask & BIT(i)) == 0) { struct phy_device *phydev; @@ -578,6 +579,7 @@ static int mdiobus_scan_bus_c22(struct mii_bus *bus) return PTR_ERR(phydev); } } + dev_warn(&bus->dev, "*** mdiobus_scan_bus_c22 return ***\n"); return 0; } @@ -585,6 +587,7 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus) { int i; + dev_warn(&bus->dev, "*** mdiobus_scan_bus_c45 call ***\n"); for (i = 0; i < PHY_MAX_ADDR; i++) { if ((bus->phy_mask & BIT(i)) == 0) { struct phy_device *phydev; @@ -598,6 +601,7 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus) return PTR_ERR(phydev); } } + dev_warn(&bus->dev, "*** mdiobus_scan_bus_c45 return ***\n"); return 0; }
And here the trimmed results from boot @ 1a136ca2e0, plus debug code.
It's not only the looping during the mv88e6xxx_wait_mask calls, but also the sheer amount of mv88e6xxx_wait_mask calls during the c45 scans. (c22: ~0.1 sec & ~150 calls, c45: 2.3-2.5 sec & ~4800 calls)
[ 0.195215] mdio_bus fixed-0: *** mdiobus_scan_bus_c22 call *** [ 0.195221] mdio_bus fixed-0: *** mdiobus_scan_bus_c22 return *** [ 0.195617] mdio_bus f1072004.mdio-mii: *** mdiobus_scan_bus_c22 call *** [ 0.195623] mdio_bus f1072004.mdio-mii: *** mdiobus_scan_bus_c22 return *** [ 0.202583] mv88e6085 f1072004.mdio-mii:10: switch 0x1760 detected: Marvell 88E6176, revision 1 [ 0.212708] mdio_bus mv88e6xxx-0: *** mdiobus_scan_bus_c22 call *** [ 0.222200] mv88e6085 f1072004.mdio-mii:10: wait_count 10, loop_count 3 ........ [ 0.315724] mv88e6085 f1072004.mdio-mii:10: wait_count 150, loop_count 76 [ 0.315908] mdio_bus mv88e6xxx-0: *** mdiobus_scan_bus_c22 return *** [ 0.315913] mdio_bus mv88e6xxx-0: *** mdiobus_scan_bus_c45 call *** [ 0.321095] mv88e6085 f1072004.mdio-mii:10: wait_count 160, loop_count 83 ........ [ 2.610380] mv88e6085 f1072004.mdio-mii:10: wait_count 4980, loop_count 1571 [ 2.613258] mdio_bus mv88e6xxx-0: *** mdiobus_scan_bus_c45 return *** [ 2.755785] mv88e6085 f1072004.mdio-mii:10: switch 0x1760 detected: Marvell 88E6176, revision 1 [ 2.766047] mdio_bus mv88e6xxx-1: *** mdiobus_scan_bus_c22 call *** [ 2.766960] mv88e6085 f1072004.mdio-mii:10: wait_count 4990, loop_count 1574 ........ [ 2.867107] mv88e6085 f1072004.mdio-mii:10: wait_count 5130, loop_count 1645 [ 2.869938] mdio_bus mv88e6xxx-1: *** mdiobus_scan_bus_c22 return *** [ 2.869943] mdio_bus mv88e6xxx-1: *** mdiobus_scan_bus_c45 call *** [ 2.871556] mv88e6085 f1072004.mdio-mii:10: wait_count 5140, loop_count 1649 ........ [ 5.371710] mv88e6085 f1072004.mdio-mii:10: wait_count 9970, loop_count 4282 [ 5.373332] mdio_bus mv88e6xxx-1: *** mdiobus_scan_bus_c45 return ***
Best regards, Klaus
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