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Commita97f8783a9("igb: unbreak I2C bit-banging on i350") introduced code to change I2C settings to bit banging unconditionally. However, this patch introduced a regression: On an Intel S2600CWR Server Board with three NICs: - 1x dual-port copper Intel I350 Gigabit Network Connection [8086:1521] (rev 01) fw 1.63, 0x80000dda - 2x quad-port SFP+ with copper SFP Avago ABCU-5700RZ Intel I350 Gigabit Fiber Network Connection [8086:1522] (rev 01) fw 1.52.0 the SFP NICs no longer get link at all. Reverting commita97f8783a9or switching to the Intel out-of-tree driver both fix the problem. Per the igb out-of-tree driver, I2C bit banging on i350 depends on support for an external thermal sensor (ETS). However, commita97f8783a9added bit banging unconditionally. Additionally, the out-of-tree driver always calls init_thermal_sensor_thresh on probe, while our driver only calls init_thermal_sensor_thresh only in igb_reset(), and only if an ETS is present, ignoring the internal thermal sensor. The affected SFPs don't provide an ETS. Per Intel, the behaviour is a result of i350 firmware requirements. This patch fixes the problem by aligning the behaviour to the out-of-tree driver: - split igb_init_i2c() into two functions: - igb_init_i2c() only performs the basic I2C initialization. - igb_set_i2c_bb() makes sure that E1000_CTRL_I2C_ENA is set and enables bit-banging. - igb_probe() only calls igb_set_i2c_bb() if an ETS is present. - igb_probe() calls init_thermal_sensor_thresh() unconditionally. - igb_reset() aligns its behaviour to igb_probe(), i. e., call igb_set_i2c_bb() if an ETS is present and call init_thermal_sensor_thresh() unconditionally. Fixes:a97f8783a9("igb: unbreak I2C bit-banging on i350") Tested-by: Mateusz Palczewski <mateusz.palczewski@intel.com> Co-developed-by: Jamie Bainbridge <jbainbri@redhat.com> Signed-off-by: Jamie Bainbridge <jbainbri@redhat.com> Signed-off-by: Corinna Vinschen <vinschen@redhat.com> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com> Link: https://lore.kernel.org/r/20230214185549.1306522-1-anthony.l.nguyen@intel.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
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