[PATCH net] ice: fix missing SMA pin initialization in DPLL subsystem

[Petr Oros <poros@redhat.com>]

The DPLL SMA/U.FL pin redesign introduced ice_dpll_sw_pin_frequency_get()
which gates frequency reporting on the pin's active flag. This flag is
determined by ice_dpll_sw_pins_update() from the PCA9575 GPIO expander
state. Before the redesign, SMA pins were exposed as direct HW
input/output pins and ice_dpll_frequency_get() returned the CGU
frequency unconditionally — the PCA9575 state was never consulted.

The PCA9575 powers on with all outputs high, setting ICE_SMA1_DIR_EN,
ICE_SMA1_TX_EN, ICE_SMA2_DIR_EN and ICE_SMA2_TX_EN. Nothing in the
driver writes the register during initialization, so
ice_dpll_sw_pins_update() sees all pins as inactive and
ice_dpll_sw_pin_frequency_get() permanently returns 0 Hz for every
SW pin.

Fix this by writing a default SMA configuration in
ice_dpll_init_info_sw_pins(): clear all SMA bits, then set SMA1 and
SMA2 as active inputs (DIR_EN=0) with U.FL1 output and U.FL2 input
disabled. Each SMA/U.FL pair shares a physical signal path so only
one pin per pair can be active at a time. U.FL pins still report
frequency 0 after this fix: U.FL1 (output-only) is disabled by
ICE_SMA1_TX_EN which keeps the TX output buffer off, and U.FL2
(input-only) is disabled by ICE_SMA2_UFL2_RX_DIS. They can be
activated by changing the corresponding SMA pin direction via dpll
netlink.

Fixes: 2dd5d03c77e2 ("ice: redesign dpll sma/u.fl pins control")
Signed-off-by: Petr Oros <poros@redhat.com>
---
 drivers/net/ethernet/intel/ice/ice_dpll.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/ethernet/intel/ice/ice_dpll.c b/drivers/net/ethernet/intel/ice/ice_dpll.c
index 53b54e395a2ed8..c2ad39bfe177db 100644
--- a/drivers/net/ethernet/intel/ice/ice_dpll.c
+++ b/drivers/net/ethernet/intel/ice/ice_dpll.c
@@ -3545,6 +3545,7 @@ static int ice_dpll_init_info_sw_pins(struct ice_pf *pf)
 	struct ice_dpll_pin *pin;
 	u32 phase_adj_max, caps;
 	int i, ret;
+	u8 data;
 
 	if (pf->hw.device_id == ICE_DEV_ID_E810C_QSFP)
 		input_idx_offset = ICE_E810_RCLK_PINS_NUM;
@@ -3604,6 +3605,22 @@ static int ice_dpll_init_info_sw_pins(struct ice_pf *pf)
 		}
 		ice_dpll_phase_range_set(&pin->prop.phase_range, phase_adj_max);
 	}
+
+	/* Initialize the SMA control register to a known-good default state.
+	 * Without this write the PCA9575 GPIO expander retains its power-on
+	 * default (all outputs high) which makes all SW pins appear inactive.
+	 * Set SMA1 and SMA2 as active inputs, disable U.FL1 output and
+	 * U.FL2 input.
+	 */
+	ret = ice_read_sma_ctrl(&pf->hw, &data);
+	if (ret)
+		return ret;
+	data &= ~ICE_ALL_SMA_MASK;
+	data |= ICE_SMA1_TX_EN | ICE_SMA2_TX_EN | ICE_SMA2_UFL2_RX_DIS;
+	ret = ice_write_sma_ctrl(&pf->hw, data);
+	if (ret)
+		return ret;
+
 	ret = ice_dpll_pin_state_update(pf, pin, ICE_DPLL_PIN_TYPE_SOFTWARE,
 					NULL);
 	if (ret)
-- 
2.52.0