linux-kernel - [PATCH net-next v3 0/4] net: dsa: mv88e6xxx: accelerate C45 scan

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Date:   Tue, 14 Mar 2023 19:26:55 +0100
From:   Klaus Kudielka <klaus.kudielka@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Richard Cochran <richardcochran@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Klaus Kudielka <klaus.kudielka@...il.com>
Subject: [PATCH net-next v3 0/4] net: dsa: mv88e6xxx: accelerate C45 scan

Starting with commit 1a136ca2e089 ("net: mdio: scan bus based on bus
capabilities for C22 and C45"), mdiobus_scan_bus_c45() is being called on
buses with MDIOBUS_NO_CAP. On a Turris Omnia (Armada 385, 88E6176 switch),
this causes a significant increase of boot time, from 1.6 seconds, to 6.3
seconds. The boot time stated here is until start of /init.

Further testing revealed that the C45 scan is indeed expensive (around
2.7 seconds, due to a huge number of bus transactions), and called twice.

Two things were suggested:
(1) to move the expensive call of mv88e6xxx_mdios_register() from
    mv88e6xxx_probe() to mv88e6xxx_setup().
(2) to mask apparently non-existing phys during probing.

Before that:
Patch #1 prepares the driver to handle the movement of
mv88e6xxx_mdios_register() to mv88e6xxx_setup() for cross-chip DSA trees.
Patch #2 is preparatory code movement, without functional change.

With those changes, boot time on the Turris Omnia is back to normal.

Link: https://lore.kernel.org/lkml/449bde236c08d5ab5e54abd73b645d8b29955894.camel@gmail.com/

Changes in v2:
Add cover letter
Extend the cleanup in mv88e6xxx_setup() to remove the mdio bus on failure 
Add patch "mask apparently non-existing phys during probing"

Changes in v3:
Add patch "don't dispose of Global2 IRQ mappings from mdiobus code"

Klaus Kudielka (3):
  net: dsa: mv88e6xxx: re-order functions
  net: dsa: mv88e6xxx: move call to mv88e6xxx_mdios_register()
  net: dsa: mv88e6xxx: mask apparently non-existing phys during probing

Vladimir Oltean (1):
  net: dsa: mv88e6xxx: don't dispose of Global2 IRQ mappings from
    mdiobus code

 drivers/net/dsa/mv88e6xxx/chip.c    | 381 ++++++++++++++--------------
 drivers/net/dsa/mv88e6xxx/global2.c |  20 +-
 2 files changed, 196 insertions(+), 205 deletions(-)

-- 
2.39.2