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linux/arch/arm64
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Hugo Villeneuve 1ed904f424 arm64: dts: imx8mn-var-som: add 20ms delay to ethernet regulator enable 
commit 26ca44bdbd upstream.

This commit is taken from Variscite linux kernel public git repository.
Original patch author: Nate Drude <nate.d@variscite.com>
See: https://github.com/varigit/linux-imx/blob/5.15-2.0.x-imx_var01/drivers/net/ethernet/freescale/fec_main.c#L3993-L4050

The ethernet phy reset was moved from the fec controller to the
mdio bus, see for example: 0e825b32c0

When the fec driver managed the reset, the regulator had time to
settle during the fec phy reset before calling of_mdiobus_register,
which probes the mii bus for the phy id to match the correct driver.

Now that the mdio bus controls the reset, the fec driver no longer has
any delay between enabling the regulator and calling of_mdiobus_register.
If the regulator voltage has not settled, the phy id will not be read
correctly and the generic phy driver will be used.

The following call tree explains in more detail:

fec_probe
  fec_reset_phy                               <- no longer introduces delay after migration to mdio reset
  fec_enet_mii_init
    of_mdiobus_register
      of_mdiobus_register_phy
        fwnode_mdiobus_register_phy
          get_phy_device                      <- mii probe for phy id to match driver happens here
          ...
          fwnode_mdiobus_phy_device_register
            phy_device_register
              mdiobus_register_device
                mdio_device_reset             <- mdio reset assert / deassert delay happens here

Add a 20ms enable delay to the regulator to fix the issue.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-12-03 07:32:11 +01:00
..
boot arm64: dts: imx8mn-var-som: add 20ms delay to ethernet regulator enable 2023-12-03 07:32:11 +01:00
configs arm64: defconfig: remove CONFIG_COMMON_CLK_NPCM8XX=y 2023-10-06 14:57:03 +02:00
crypto crypto: arm64/aes-neonbs - fix crash with CFI enabled 2023-05-11 23:03:02 +09:00
hyperv hyperv: simplify and rename generate_guest_id 2022-09-28 13:36:56 +00:00
include arm64: mm: Fix "rodata=on" when CONFIG_RODATA_FULL_DEFAULT_ENABLED=y 2023-12-03 07:32:08 +01:00
kernel arm64: errata: Add Cortex-A520 speculative unprivileged load workaround 2023-10-10 22:00:39 +02:00
kvm clocksource/drivers/arm_arch_timer: limit XGene-1 workaround 2023-11-20 11:52:01 +01:00
lib arm64: csum: Fix OoB access in IP checksum code for negative lengths 2023-09-13 09:43:01 +02:00
mm arm64: mm: Fix "rodata=on" when CONFIG_RODATA_FULL_DEFAULT_ENABLED=y 2023-12-03 07:32:08 +01:00
net bpf: Remove prog->active check for bpf_lsm and bpf_iter 2023-09-19 12:28:03 +02:00
tools arm64: errata: Add Cortex-A520 speculative unprivileged load workaround 2023-10-10 22:00:39 +02:00
xen xen: allow pv-only hypercalls only with CONFIG_XEN_PV 2021-11-02 08:11:01 -05:00
Kbuild kbuild: use more subdir- for visiting subdirectories while cleaning 2021-10-24 13:49:46 +09:00
Kconfig arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM IAS 15.x or newer 2023-11-28 17:07:10 +00:00
Kconfig.debug arm64: remove TEXT_OFFSET randomization 2020-06-15 13:10:59 +01:00
Kconfig.platforms ARM: SoC code changes for 6.1 2022-10-06 11:22:25 -07:00
Makefile Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00