wifi: iwlwifi: fix merge damage related to iwl_pci_resume

The changes I made in
wifi: iwlwifi: don't warn if the NIC is gone in resume
conflicted with a major rework done in this area.
The merge de-facto removed my changes.
Re-add them.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Link: https://patch.msgid.link/20250603091754.70182-1-emmanuel.grumbach@intel.com
Fixes: 06c4b20 ("Merge tag 'iwlwifi-next-2025-05-15' of https://git.kernel.org/pub/scm/linux/kernel/git/iwlwifi/iwlwifi-next")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: egrumbach

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

@@ -1501,11 +1501,27 @@ static int _iwl_pci_resume(struct device *device, bool restore)
 	 * Scratch value was altered, this means the device was powered off, we
 	 * 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.
+	 * but not bits [15:8]. So if we have bits set in lower word, assume
+	 * the device is alive.
+	 * For older devices, just try silently to grab the NIC.
 	 */
-	if (trans->mac_cfg->device_family >= IWL_DEVICE_FAMILY_BZ &&
-	    !iwl_read32(trans, CSR_FUNC_SCRATCH))
-		device_was_powered_off = true;
+	if (trans->mac_cfg->device_family >= IWL_DEVICE_FAMILY_BZ) {
+		if (!(iwl_read32(trans, CSR_FUNC_SCRATCH) &
+		      CSR_FUNC_SCRATCH_POWER_OFF_MASK))
+			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;