[PATCH v1] Bluetooth: btintel_pcie: Retry FLR on device lock contention

[Ravindra <ravindra@intel.com>]

Several paths request an FLR asynchronously, including S3/S4 resume,
resume recovery, HCI reset, and hardware-error recovery. When a request
comes from a PM callback, reset work may run before the PM core releases
the PCI device lock. pci_try_reset_function() then returns -EAGAIN
without attempting the FLR. Other FLR requests can encounter the same
error if another operation holds the device lock.

Retry the FLR on -EAGAIN. If all attempts fail, clear the recovery
in-progress flag so a later reset request can try again.

Fixes: 9c36951474d8 ("Bluetooth: btintel_pcie: Refactor FLR to use device_reprobe()")
Signed-off-by: Ravindra <ravindra@intel.com>
---
 drivers/bluetooth/btintel_pcie.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/bluetooth/btintel_pcie.c b/drivers/bluetooth/btintel_pcie.c
index 3a555aa50c87..251dd4e2ceb4 100644
--- a/drivers/bluetooth/btintel_pcie.c
+++ b/drivers/bluetooth/btintel_pcie.c
@@ -3743,7 +3743,7 @@ static void btintel_pcie_perform_pldr(struct btintel_pcie_data *data)
 static int btintel_pcie_perform_flr(struct btintel_pcie_data *data)
 {
 	struct pci_dev *pdev = data->pdev;
-	int err;
+	int err, retry;
 
 	/* pci_try_reset_function() avoids the device_lock ABBA against
 	 * btintel_pcie_remove(): .remove() runs with device_lock held and
@@ -3751,7 +3751,16 @@ static int btintel_pcie_perform_flr(struct btintel_pcie_data *data)
 	 * pci_reset_function() would deadlock by trying to re-acquire
 	 * device_lock here.
 	 */
-	err = pci_try_reset_function(pdev);
+	/* PM callbacks hold the device lock, so the queued resume reset may
+	 * run before the callback releases it. Retry after that lock is dropped.
+	 */
+	for (retry = 0; retry < 3; retry++) {
+		err = pci_try_reset_function(pdev);
+		if (err != -EAGAIN)
+			break;
+
+		usleep_range(1000, 2000);
+	}
 	if (err) {
 		BT_ERR("Failed resetting the pcie device (%d)", err);
 		return err;
@@ -3817,6 +3826,7 @@ static void btintel_pcie_reset_work(struct work_struct *wk)
 		enable_work(&data->hwexp_work);
 		enable_work(&data->fwtrigger_work);
 		enable_work(&data->mbox_work);
+		clear_bit(BTINTEL_PCIE_RECOVERY_IN_PROGRESS, &data->flags);
 	}
 
 out:
@@ -3841,10 +3851,9 @@ static void btintel_pcie_reset_work(struct work_struct *wk)
  *     in-flight one (whose recovery will reinitialize the device
  *     regardless of the dropped trigger's variant).
  *
- * The bit is cleared only by .remove() / re-probe via fresh devm
- * allocation, which is the intended one-shot semantics: a reset
- * tears down and re-probes 'data', so there is no "in-flight"
- * reset to follow up after device_reprobe() succeeds.
+ * A successful reset clears the bit through .remove() / re-probe via
+ * fresh devm allocation. A failed FLR clears it in reset_work so a
+ * later request can retry; there is no in-flight reset after failure.
  */
 static void btintel_pcie_request_reset(struct btintel_pcie_data *data,
 				       enum btintel_pcie_reset_type type)
-- 
2.43.0