Re: [Intel-wired-lan] [net-next, v4, 9/9] ice: dpll: Support E825-C SyncE and dynamic pin discovery

[Ivan Vecera]

On 2/3/26 5:11 PM, Simon Horman wrote:
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---
ice: dpll: Support E825-C SyncE and dynamic pin discovery

This patch implements SyncE support for the E825-C Ethernet controller
using the DPLL subsystem, with dynamic pin discovery via firmware (ACPI)
and asynchronous registration using the DPLL notifier chain.

diff --git a/drivers/net/ethernet/intel/ice/ice_dpll.c 
b/drivers/net/ethernet/intel/ice/ice_dpll.c
index 4eca62688d83..a8c99e49bfae 100644
--- a/drivers/net/ethernet/intel/ice/ice_dpll.c
+++ b/drivers/net/ethernet/intel/ice/ice_dpll.c
[ ... ]

@@ -528,6 +529,92 @@ ice_dpll_pin_disable(struct ice_hw *hw, struct 
ice_dpll_pin *pin,
        return ret;
  }

+/**
+ * ice_dpll_rclk_update - updates the state of rclk pin on a device
+ * @pf: private board struct
+ * @pin: pointer to a pin
+ * @port_num: port number
+ *
+ * Update struct holding pin states info, states are separate for each parent
+ *
+ * Context: Called under pf->dplls.lock
+ * Return:
+ * * 0 - OK
+ * * negative - error
+ */
+static int ice_dpll_rclk_update(struct ice_pf *pf, struct ice_dpll_pin *pin,
+                               u8 port_num)
+{
+       int ret;
+
+       for (u8 parent = 0; parent < pf->dplls.rclk.num_parents; parent++) {
+               ret = ice_aq_get_phy_rec_clk_out(&pf->hw, &parent, &port_num,
+                                                &pin->flags[parent], NULL);
Is it safe to pass &parent as an output parameter when it's also the loop
counter? Looking at ice_aq_get_phy_rec_clk_out():

     int ice_aq_get_phy_rec_clk_out(struct ice_hw *hw, u8 *phy_output, ...)
     {
         cmd->phy_output = *phy_output;  // Read as input
         status = ice_aq_send_cmd(hw, &desc, NULL, 0, NULL);
         if (!status) {
             *phy_output = cmd->phy_output;  // Write back from firmware
         ...

The firmware could potentially return a different value than was sent,
which would be written back to 'parent', corrupting the loop counter.

This corrupted value is then used as an array index:

+               if (ret)
+                       return ret;
+
+               ice_dpll_pin_store_state(pin, parent,
+                                        ICE_AQC_GET_PHY_REC_CLK_OUT_OUT_EN &
+                                        pin->flags[parent]);
Both pin->flags[parent] and pin->state[parent] (inside
ice_dpll_pin_store_state) could access out of bounds if firmware returns
a value >= ICE_DPLL_RCLK_NUM_MAX (which is 2).

Would it be safer to use a separate variable for the phy_output parameter
and validate that firmware echoes back the expected value?

Yes, there should be a separate variable like in previous code prior
this refactor...

<snip>
        case ICE_DPLL_PIN_TYPE_RCLK_INPUT:
-               for (parent = 0; parent < pf->dplls.rclk.num_parents;
-                    parent++) {
-                       u8 p = parent; <--- HERE
-
-                       ret = ice_aq_get_phy_rec_clk_out(&pf->hw, &p,
-                                                        &port_num,
- 
&pin->flags[parent],
-                                                        NULL);
</snip>

Arek, I will fix it by myself.

Thanks,
Ivan