On dual complex E825 only complex 0 has a functional CGU and the second
complex reaches it through cgu_peer, so PFs of both complexes share the
CGU registers R10 and R11. They read, modify and write them when the
state of an RCLK pin changes, and ice_ptp_link_change() rewrites R10 when
a link changes, under the pf->dplls.lock of their own PF only.

ice_ptp_link_change() does not hold dpll_lock, so it can already overwrite
an update of another PF. RCLK callbacks are serialized by dpll_lock, but
the DPLL core is going to serialize callbacks per (module, clock_id), and
each complex has its own DSN and so its own clock_id. With that change, a
test toggling RCLK pins of both complexes lost an update.

Add a mutex to struct ice_adapter, which all E825C PFs share, and hold it
around these sequences.

Signed-off-by: Ivan Vecera <[email protected]>
---
 drivers/net/ethernet/intel/ice/ice_adapter.c |  2 ++
 drivers/net/ethernet/intel/ice/ice_adapter.h |  4 ++++
 drivers/net/ethernet/intel/ice/ice_dpll.c    | 11 ++++++-----
 drivers/net/ethernet/intel/ice/ice_dpll.h    |  4 ++++
 drivers/net/ethernet/intel/ice/ice_ptp.c     |  2 ++
 drivers/net/ethernet/intel/ice/ice_tspll.c   |  4 ++--
 6 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.c 
b/drivers/net/ethernet/intel/ice/ice_adapter.c
index 536923b6ae979d..aa2d8addae5bef 100644
--- a/drivers/net/ethernet/intel/ice/ice_adapter.c
+++ b/drivers/net/ethernet/intel/ice/ice_adapter.c
@@ -72,6 +72,7 @@ static struct ice_adapter *ice_adapter_new(struct pci_dev 
*pdev)
        spin_lock_init(&adapter->txq_ctx_lock);
        for (int i = 0; i < ARRAY_SIZE(adapter->cpi_phy_lock); i++)
                mutex_init(&adapter->cpi_phy_lock[i]);
+       mutex_init(&adapter->cgu_synce_lock);
        refcount_set(&adapter->refcount, 1);
 
        spin_lock_init(&adapter->ports.lock);
@@ -85,6 +86,7 @@ static void ice_adapter_free(struct ice_adapter *adapter)
        WARN_ON(!list_empty(&adapter->ports.list));
        for (int i = 0; i < ARRAY_SIZE(adapter->cpi_phy_lock); i++)
                mutex_destroy(&adapter->cpi_phy_lock[i]);
+       mutex_destroy(&adapter->cgu_synce_lock);
 
        cleanup_srcu_struct(&adapter->ports.srcu);
 
diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.h 
b/drivers/net/ethernet/intel/ice/ice_adapter.h
index c61bd645e460de..fd5585005d91ba 100644
--- a/drivers/net/ethernet/intel/ice/ice_adapter.h
+++ b/drivers/net/ethernet/intel/ice/ice_adapter.h
@@ -41,6 +41,8 @@ struct ice_port_list {
  * @txq_ctx_lock: Spinlock protecting access to the GLCOMM_QTX_CNTX_CTL 
register
  * @cpi_phy_lock: Per-PHY mutex serializing CPI REQ/ACK transactions.
  *               Index 0 = PHY0, index 1 = PHY1. Used on E825C devices.
+ * @cgu_synce_lock: Mutex serializing changes of the CGU registers R10 and R11,
+ *                  which all PFs reach. Used on E825C devices.
  * @ctrl_pf: Control PF of the adapter
  * @ports: Ports list
  * @index: 64-bit index cached for collision detection on 32bit systems
@@ -53,6 +55,8 @@ struct ice_adapter {
        spinlock_t txq_ctx_lock;
        /* Serialize CPI REQ/ACK transactions per PHY (E825C only) */
        struct mutex cpi_phy_lock[ICE_E825_MAX_PHYS];
+       /* Serialize changes of the SyncE CGU registers (E825C only) */
+       struct mutex cgu_synce_lock;
 
        struct ice_pf *ctrl_pf;
        struct ice_port_list ports;
diff --git a/drivers/net/ethernet/intel/ice/ice_dpll.c 
b/drivers/net/ethernet/intel/ice/ice_dpll.c
index bdbcf7af296eb4..d6302409a2dacf 100644
--- a/drivers/net/ethernet/intel/ice/ice_dpll.c
+++ b/drivers/net/ethernet/intel/ice/ice_dpll.c
@@ -2027,7 +2027,7 @@ ice_dpll_phase_offset_get(const struct dpll_pin *pin, 
void *pin_priv,
  *
  * DPLL subsystem callback. Set proper signals to recover clock from port.
  *
- * Context: Called under pf->dplls.lock
+ * Context: Called under pf->dplls.lock, acquires adapter->cgu_synce_lock
  * Return:
  * * 0 - success
  * * negative - error
@@ -2035,14 +2035,15 @@ ice_dpll_phase_offset_get(const struct dpll_pin *pin, 
void *pin_priv,
 static int ice_dpll_synce_update_e825c(struct ice_hw *hw, bool ena,
                                       u32 port_num, enum ice_synce_clk output)
 {
+       struct ice_pf *pf = hw->back;
        int err;
 
+       mutex_lock(&pf->adapter->cgu_synce_lock);
        /* configure the mux to deliver proper signal to DPLL from the MUX */
        err = ice_tspll_cfg_bypass_mux_e825c(hw, ena, port_num, output);
-       if (err)
-               return err;
-
-       err = ice_tspll_cfg_synce_ethdiv_e825c(hw, output);
+       if (!err)
+               err = ice_tspll_cfg_synce_ethdiv_e825c(hw, output);
+       mutex_unlock(&pf->adapter->cgu_synce_lock);
        if (err)
                return err;
 
diff --git a/drivers/net/ethernet/intel/ice/ice_dpll.h 
b/drivers/net/ethernet/intel/ice/ice_dpll.h
index bce0bea9a664bc..4ba76e2e2e0b01 100644
--- a/drivers/net/ethernet/intel/ice/ice_dpll.h
+++ b/drivers/net/ethernet/intel/ice/ice_dpll.h
@@ -158,6 +158,7 @@ struct ice_dpll {
  *     txclk_notify_rwsem (read)
  *       -> pf->dplls.lock
  *         -> ctrl_pf->dplls.lock
+ *         -> adapter->cgu_synce_lock
  *
  *   - @lock serializes all DPLL state mutations on this PF. When the
  *     controlling PF's lock must also be taken (e.g. updating the shared
@@ -169,6 +170,9 @@ struct ice_dpll {
  *     dpll_*_change_ntf() calls. ice_dpll_deinit() takes the write side
  *     standalone (not nested under any other lock) to drain in-flight
  *     readers before pins and the TXC DPLL device are freed.
+ *   - adapter->cgu_synce_lock serializes changes of the CGU registers R10 and
+ *     R11. All PFs of a dual complex E825 reach one CGU, so @lock does not
+ *     cover them.
  */
 struct ice_dplls {
        struct kthread_worker *kworker;
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c 
b/drivers/net/ethernet/intel/ice/ice_ptp.c
index 3df08714510da5..4d4b6aaaf30c29 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
@@ -1395,7 +1395,9 @@ void ice_ptp_link_change(struct ice_pf *pf, bool linkup)
                                break;
                        }
 
+                       mutex_lock(&pf->adapter->cgu_synce_lock);
                        err = ice_tspll_cfg_synce_ethdiv_e825c(hw, clk_pin);
+                       mutex_unlock(&pf->adapter->cgu_synce_lock);
                        if (active && err) {
                                dev_err_once(ice_pf_to_dev(pf),
                                             "Failed to configure SyncE ETH 
divider for pin %d, err %d\n",
diff --git a/drivers/net/ethernet/intel/ice/ice_tspll.c 
b/drivers/net/ethernet/intel/ice/ice_tspll.c
index 85bacb7c3a7903..b99e02cfe559bd 100644
--- a/drivers/net/ethernet/intel/ice/ice_tspll.c
+++ b/drivers/net/ethernet/intel/ice/ice_tspll.c
@@ -792,7 +792,7 @@ int ice_tspll_bypass_mux_active_e825c(struct ice_hw *hw, u8 
port, bool *active,
  *
  * Set reference clock source and output clock selection.
  *
- * Context: Called under pf->dplls.lock
+ * Context: Called under pf->dplls.lock and adapter->cgu_synce_lock
  * Return:
  * * 0 - success
  * * negative - error
@@ -898,7 +898,7 @@ static int ice_tspll_get_div_e825c(u16 link_speed, unsigned 
int *divider)
  *
  * Set the correct CGU divider for RCLKA or RCLKB.
  *
- * Context: Called under pf->dplls.lock
+ * Context: Called under pf->dplls.lock and adapter->cgu_synce_lock
  * Return:
  * * 0 - success
  * * negative - error
-- 
2.56.0

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