Greg Patrick
8ac44d24c3
An SFP cage (compatible "sff,sfp") whose MOD_DEF0 signal is not wired to a GPIO currently falls back to sff_gpio_get_state(), which unconditionally reports the module as present. An empty cage therefore fails its probe and is parked in SFP_MOD_ERROR forever; because SFP_F_PRESENT never deasserts there is no REMOVE event to recover the state machine, so a module inserted after boot is never detected, and empty cages spam -EIO at boot. This affects boards that route none of the cage presence signal to a software-readable input. On the NicGiga S100-0800S-M (RTL9303, 8x SFP+) the cage I2C bus is the switch's SMBus master; TX_DISABLE is driven via a PCA9534 I/O expander, but no MOD_ABS/MOD_DEF0 line reaches a readable GPIO (the RTL9303 gpio0 lines read stuck-low, the single PCA9534 is fully consumed by TX_DISABLE, and there is no RTL8231). The Horaco ZX-SW82TS-L2P (RTL9302D, 2x SFP+) is independently affected in the same way. For such an SFP cage, derive presence from a throttled single-byte I2C read of the module EEPROM instead: a successful read asserts SFP_F_PRESENT, R_PROBE_ABSENT consecutive failures clear it (to ride out a transient error on a live module). The existing poll then emits SFP_E_INSERT / SFP_E_REMOVE normally, giving working hot-plug and silencing the boot-time -EIO spam on empty cages. Presence is re-probed every T_PROBE_PRESENT, so insertion is detected within that interval and removal within T_PROBE_PRESENT * R_PROBE_ABSENT. A soldered-down module (compatible "sff,sff") has no presence signal and is genuinely always present, so it continues to use sff_gpio_get_state(); the new path is gated on the cage type advertising SFP_F_PRESENT. Signed-off-by: Greg Patrick <gregspatrick@hotmail.com> Tested-by: Manuel Stocker <mensi@mensi.ch> Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com> Link: https://patch.msgid.link/20260611175341.2223184-1-gregspatrick@hotmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. 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