wifi: iwlwifi: don't warn if the NIC is gone in resume

Some BIOSes decide to power gate the WLAN device during S3. Since
iwlwifi doesn't expect this, it gets very noisy reporting that the
device is no longer available. Wifi is still available because iwlwifi
recovers, but it spews scary prints in the log.

Fix that by failing gracefully.

Fixes: e8bb19c ("wifi: iwlwifi: support fast resume")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219597
Signed-off-by: Emmanuel Grumbach <[email protected]>
Signed-off-by: Miri Korenblit <[email protected]>
Link: https://patch.msgid.link/20250420095642.d8d58146c829.I569ca15eaaa774d633038a749cc6ec7448419714@changeid
Signed-off-by: Johannes Berg <[email protected]>

Author: egrumbach

drivers/net/wireless/intel/iwlwifi/iwl-trans.c

@@ -555,7 +555,6 @@ void __releases(nic_access)
 iwl_trans_release_nic_access(struct iwl_trans *trans)
 {
 	iwl_trans_pcie_release_nic_access(trans);
-	__release(nic_access);
 }
 IWL_EXPORT_SYMBOL(iwl_trans_release_nic_access);
 

drivers/net/wireless/intel/iwlwifi/pcie/drv.c

@@ -1737,10 +1737,24 @@ static int _iwl_pci_resume(struct device *device, bool restore)
 	 * need to reset it completely.
 	 * Note: MAC (bits 0:7) will be cleared upon suspend even with wowlan,
 	 * so assume that any bits there mean that the device is usable.
+	 * For older devices, just try silently to grab the NIC.
 	 */
-	if (trans->trans_cfg->device_family >= IWL_DEVICE_FAMILY_BZ &&
-	    !iwl_read32(trans, CSR_FUNC_SCRATCH))
-		device_was_powered_off = true;
+	if (trans->trans_cfg->device_family >= IWL_DEVICE_FAMILY_BZ) {
+		if (!iwl_read32(trans, CSR_FUNC_SCRATCH))
+			device_was_powered_off = true;
+	} else {
+		/*
+		 * bh are re-enabled by iwl_trans_pcie_release_nic_access,
+		 * so re-enable them if _iwl_trans_pcie_grab_nic_access fails.
+		 */
+		local_bh_disable();
+		if (_iwl_trans_pcie_grab_nic_access(trans, true)) {
+			iwl_trans_pcie_release_nic_access(trans);
+		} else {
+			device_was_powered_off = true;
+			local_bh_enable();
+		}
+	}
 
 	if (restore || device_was_powered_off) {
 		trans->state = IWL_TRANS_NO_FW;

drivers/net/wireless/intel/iwlwifi/pcie/internal.h

@@ -558,10 +558,10 @@ void iwl_trans_pcie_free(struct iwl_trans *trans);
 void iwl_trans_pcie_free_pnvm_dram_regions(struct iwl_dram_regions *dram_regions,
 					   struct device *dev);
 
-bool __iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans);
-#define _iwl_trans_pcie_grab_nic_access(trans)			\
+bool __iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans, bool silent);
+#define _iwl_trans_pcie_grab_nic_access(trans, silent)		\
 	__cond_lock(nic_access_nobh,				\
-		    likely(__iwl_trans_pcie_grab_nic_access(trans)))
+		    likely(__iwl_trans_pcie_grab_nic_access(trans, silent)))
 
 void iwl_trans_pcie_check_product_reset_status(struct pci_dev *pdev);
 void iwl_trans_pcie_check_product_reset_mode(struct pci_dev *pdev);
@@ -1105,7 +1105,8 @@ void iwl_trans_pcie_set_bits_mask(struct iwl_trans *trans, u32 reg,
 int iwl_trans_pcie_read_config32(struct iwl_trans *trans, u32 ofs,
 				 u32 *val);
 bool iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans);
-void iwl_trans_pcie_release_nic_access(struct iwl_trans *trans);
+void __releases(nic_access_nobh)
+iwl_trans_pcie_release_nic_access(struct iwl_trans *trans);
 
 /* transport gen 1 exported functions */
 void iwl_trans_pcie_fw_alive(struct iwl_trans *trans, u32 scd_addr);

drivers/net/wireless/intel/iwlwifi/pcie/trans.c

@@ -2406,7 +2406,7 @@ EXPORT_SYMBOL(iwl_trans_pcie_reset);
  * This version doesn't disable BHs but rather assumes they're
  * already disabled.
  */
-bool __iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans)
+bool __iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans, bool silent)
 {
 	int ret;
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
@@ -2458,6 +2458,11 @@ bool __iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans)
 	if (unlikely(ret < 0)) {
 		u32 cntrl = iwl_read32(trans, CSR_GP_CNTRL);
 
+		if (silent) {
+			spin_unlock(&trans_pcie->reg_lock);
+			return false;
+		}
+
 		WARN_ONCE(1,
 			  "Timeout waiting for hardware access (CSR_GP_CNTRL 0x%08x)\n",
 			  cntrl);
@@ -2489,7 +2494,7 @@ bool iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans)
 	bool ret;
 
 	local_bh_disable();
-	ret = __iwl_trans_pcie_grab_nic_access(trans);
+	ret = __iwl_trans_pcie_grab_nic_access(trans, false);
 	if (ret) {
 		/* keep BHs disabled until iwl_trans_pcie_release_nic_access */
 		return ret;
@@ -2498,7 +2503,8 @@ bool iwl_trans_pcie_grab_nic_access(struct iwl_trans *trans)
 	return false;
 }
 
-void iwl_trans_pcie_release_nic_access(struct iwl_trans *trans)
+void __releases(nic_access_nobh)
+iwl_trans_pcie_release_nic_access(struct iwl_trans *trans)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 
@@ -2525,6 +2531,7 @@ void iwl_trans_pcie_release_nic_access(struct iwl_trans *trans)
 	 * scheduled on different CPUs (after we drop reg_lock).
 	 */
 out:
+	__release(nic_access_nobh);
 	spin_unlock_bh(&trans_pcie->reg_lock);
 }
 

drivers/net/wireless/intel/iwlwifi/pcie/tx.c

@@ -1021,7 +1021,7 @@ static int iwl_pcie_set_cmd_in_flight(struct iwl_trans *trans,
 	 * returned. This needs to be done only on NICs that have
 	 * apmg_wake_up_wa set (see above.)
 	 */
-	if (!_iwl_trans_pcie_grab_nic_access(trans))
+	if (!_iwl_trans_pcie_grab_nic_access(trans, false))
 		return -EIO;
 
 	/*