Re: [PATCH net-next 3/5] net: sfp: configure/destroy I2C mdiobus on transceiver plug/unplug
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Date: 2020-10-29 13:31:03
On Wed, Oct 28, 2020 at 11:14:25PM +0100, Marek Behún wrote:
quoted hunk ↗ jump to hunk
Instead of configuring the I2C mdiobus when SFP driver is probed, configure/destroy the mdiobus when SFP transceiver is plugged/unplugged. This way we can tell the mdio-i2c code which protocol to use for each SFP transceiver. Signed-off-by: Marek Behún <kabel@kernel.org> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Russell King <redacted> --- drivers/net/phy/sfp.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c index b1f9fc3a5584..a392d5fc6ab4 100644 --- a/drivers/net/phy/sfp.c +++ b/drivers/net/phy/sfp.c@@ -399,9 +399,6 @@ static int sfp_i2c_write(struct sfp *sfp, bool a2, u8 dev_addr, void *buf, static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c) { - struct mii_bus *i2c_mii; - int ret; - if (!i2c_check_functionality(i2c, I2C_FUNC_I2C)) return -EINVAL;@@ -409,7 +406,15 @@ static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c) sfp->read = sfp_i2c_read; sfp->write = sfp_i2c_write; - i2c_mii = mdio_i2c_alloc(sfp->dev, i2c, MDIO_I2C_DEFAULT); + return 0; +} + +static int sfp_i2c_mdiobus_configure(struct sfp *sfp, enum mdio_i2c_type type) +{ + struct mii_bus *i2c_mii; + int ret; + + i2c_mii = mdio_i2c_alloc(sfp->dev, sfp->i2c, type); if (IS_ERR(i2c_mii)) return PTR_ERR(i2c_mii);@@ -427,6 +432,12 @@ static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c) return 0; } +static void sfp_i2c_mdiobus_destroy(struct sfp *sfp) +{ + mdiobus_unregister(sfp->i2c_mii); + sfp->i2c_mii = NULL; +} + /* Interface */ static int sfp_read(struct sfp *sfp, bool a2, u8 addr, void *buf, size_t len) {@@ -1768,6 +1779,11 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report) else sfp->module_t_start_up = T_START_UP; + /* Configure mdiobus */ + ret = sfp_i2c_mdiobus_configure(sfp, MDIO_I2C_DEFAULT); + if (ret < 0) + return ret; +
return sfp_i2c_mdiobus_configure(sfp, MDIO_I2C_DEFAULT); would be a simpler way to write this. However, I suggest handling this elsewhere due to the point below.
quoted hunk ↗ jump to hunk
@@ -1778,6 +1794,8 @@ static void sfp_sm_mod_remove(struct sfp *sfp) sfp_hwmon_remove(sfp); + sfp_i2c_mdiobus_destroy(sfp); +
This doesn't seem like the right place to handle this. This is called from the module state machine (sfp_sm_module()) which is run before the main state machine (sfp_sm_main()). The PHY is unregistered in the main state machine, which means you're destroying the MII bus before the PHY. I guess what saves us from crashing is the refcounting, but this doesn't seem to me to be particularly good. Maybe create the MII bus after the "init_done" label, and destroy it after we've called sfp_sm_phy_detach() ? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!