Messages in this thread Patch in this message | | | From | Andrew Halaney <> | Date | Tue, 21 Nov 2023 16:10:37 -0600 | Subject | [PATCH net-next] net: phy: mdio_device: Reset device only when necessary |
| |
Currently the phy reset sequence is as shown below for a devicetree described mdio phy on boot:
1. Assert the phy_device's reset as part of registering 2. Deassert the phy_device's reset as part of registering 3. Deassert the phy_device's reset as part of phy_probe 4. Deassert the phy_device's reset as part of phy_hw_init
The extra two deasserts include waiting the deassert delay afterwards, which is adding unnecessary delay.
Here's some snipped tracing output using the following command line params "trace_event=gpio:* trace_options=stacktrace" illustrating the reset handling and where its coming from:
/* Assert */ systemd-udevd-283 [002] ..... 6.780434: gpio_value: 544 set 0 systemd-udevd-283 [002] ..... 6.783849: <stack trace> => gpiod_set_raw_value_commit => gpiod_set_value_nocheck => gpiod_set_value_cansleep => mdio_device_reset => mdiobus_register_device => phy_device_register => fwnode_mdiobus_phy_device_register => fwnode_mdiobus_register_phy => __of_mdiobus_register => stmmac_mdio_register => stmmac_dvr_probe => stmmac_pltfr_probe => devm_stmmac_pltfr_probe => qcom_ethqos_probe => platform_probe
/* Deassert */ systemd-udevd-283 [002] ..... 6.802480: gpio_value: 544 set 1 systemd-udevd-283 [002] ..... 6.805886: <stack trace> => gpiod_set_raw_value_commit => gpiod_set_value_nocheck => gpiod_set_value_cansleep => mdio_device_reset => phy_device_register => fwnode_mdiobus_phy_device_register => fwnode_mdiobus_register_phy => __of_mdiobus_register => stmmac_mdio_register => stmmac_dvr_probe => stmmac_pltfr_probe => devm_stmmac_pltfr_probe => qcom_ethqos_probe => platform_probe
/* Deassert */ systemd-udevd-283 [002] ..... 6.882601: gpio_value: 544 set 1 systemd-udevd-283 [002] ..... 6.886014: <stack trace> => gpiod_set_raw_value_commit => gpiod_set_value_nocheck => gpiod_set_value_cansleep => mdio_device_reset => phy_probe => really_probe => __driver_probe_device => driver_probe_device => __device_attach_driver => bus_for_each_drv => __device_attach => device_initial_probe => bus_probe_device => device_add => phy_device_register => fwnode_mdiobus_phy_device_register => fwnode_mdiobus_register_phy => __of_mdiobus_register => stmmac_mdio_register => stmmac_dvr_probe => stmmac_pltfr_probe => devm_stmmac_pltfr_probe => qcom_ethqos_probe => platform_probe
/* Deassert */ NetworkManager-477 [000] ..... 7.023144: gpio_value: 544 set 1 NetworkManager-477 [000] ..... 7.026596: <stack trace> => gpiod_set_raw_value_commit => gpiod_set_value_nocheck => gpiod_set_value_cansleep => mdio_device_reset => phy_init_hw => phy_attach_direct => phylink_fwnode_phy_connect => __stmmac_open => stmmac_open
There's a lot of paths where the device is getting its reset asserted and deasserted. Let's track the state and only actually do the assert/deassert when it changes.
Reported-by: Sagar Cheluvegowda <quic_scheluve@quicinc.com> Signed-off-by: Andrew Halaney <ahalaney@redhat.com> --- This patch isn't the prettiest thing in the world, but the myriad of call paths that lead to touching the reset gpio is proving daunting to me. I originally tried to remove some of the reset calls in various places, but after staring at the different call paths I decided this was safer, I am not confident I covered all the corner cases when going about this by removing the extra phy_device_reset/mdio_device_reset calls. --- drivers/net/phy/mdio_device.c | 5 +++++ include/linux/mdio.h | 1 + 2 files changed, 6 insertions(+)
diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c index 044828d081d2..d2b9e62edaaa 100644 --- a/drivers/net/phy/mdio_device.c +++ b/drivers/net/phy/mdio_device.c @@ -122,6 +122,9 @@ void mdio_device_reset(struct mdio_device *mdiodev, int value) if (!mdiodev->reset_gpio && !mdiodev->reset_ctrl) return; + if (mdiodev->reset_state == value) + return; + if (mdiodev->reset_gpio) gpiod_set_value_cansleep(mdiodev->reset_gpio, value); @@ -135,6 +138,8 @@ void mdio_device_reset(struct mdio_device *mdiodev, int value) d = value ? mdiodev->reset_assert_delay : mdiodev->reset_deassert_delay; if (d) fsleep(d); + + mdiodev->reset_state = value; } EXPORT_SYMBOL(mdio_device_reset); diff --git a/include/linux/mdio.h b/include/linux/mdio.h index 007fd9c3e4b6..79ceee3c8673 100644 --- a/include/linux/mdio.h +++ b/include/linux/mdio.h @@ -38,6 +38,7 @@ struct mdio_device { /* Bus address of the MDIO device (0-31) */ int addr; int flags; + int reset_state; struct gpio_desc *reset_gpio; struct reset_control *reset_ctrl; unsigned int reset_assert_delay; --- base-commit: 07b677953b9dca02928be323e2db853511305fa9 change-id: 20231121-net-phy-reset-once-1e2323982ae0 Best regards, -- Andrew Halaney <ahalaney@redhat.com>
| |