ath11k: Set IRQ affinity to CPU0 in case of one MSI vector

With VT-d disabled on Intel platform, ath11k gets only one MSI
vector. In that case, ath11k does not free IRQ when doing suspend,
hence the kernel has to migrate it to CPU0 (if it was affine to
other CPUs) and allocates a new MSI vector. However, ath11k has
no chance to reconfig it to HW srngs during this phase, thus
ath11k fails to resume.

This issue can be fixed by setting IRQ affinity to CPU0 before
request_irq is called. With such affinity, migration will not
happen and thus the vector keeps unchanged during suspend/resume.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Signed-off-by: Baochen Qiang <bqiang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211026041732.5323-1-bqiang@codeaurora.org

drivers/net/wireless/ath/ath11k/pci.c

@@ -843,6 +843,15 @@ static int ath11k_pci_ext_irq_config(struct ath11k_base *ab)
 	return 0;
 }
 
+static int ath11k_pci_set_irq_affinity_hint(struct ath11k_pci *ab_pci,
+					    const struct cpumask *m)
+{
+	if (test_bit(ATH11K_PCI_FLAG_MULTI_MSI_VECTORS, &ab_pci->flags))
+		return 0;
+
+	return irq_set_affinity_hint(ab_pci->pdev->irq, m);
+}
+
 static int ath11k_pci_config_irq(struct ath11k_base *ab)
 {
 	struct ath11k_pci *ab_pci = ath11k_pci_priv(ab);
@@ -859,6 +868,12 @@ static int ath11k_pci_config_irq(struct ath11k_base *ab)
 	if (ret)
 		return ret;
 
+	ret = ath11k_pci_set_irq_affinity_hint(ab_pci, cpumask_of(0));
+	if (ret) {
+		ath11k_err(ab, "failed to set irq affinity %d\n", ret);
+		return ret;
+	}
+
 	/* Configure CE irqs */
 	for (i = 0, msi_data_idx = 0; i < ab->hw_params.ce_count; i++) {
 		if (ath11k_ce_get_attr_flags(ab, i) & CE_ATTR_DIS_INTR)
@@ -878,7 +893,7 @@ static int ath11k_pci_config_irq(struct ath11k_base *ab)
 		if (ret) {
 			ath11k_err(ab, "failed to request irq %d: %d\n",
 				   irq_idx, ret);
-			return ret;
+			goto err_irq_affinity_cleanup;
 		}
 
 		ab->irq_num[irq_idx] = irq;
@@ -889,9 +904,13 @@ static int ath11k_pci_config_irq(struct ath11k_base *ab)
 
 	ret = ath11k_pci_ext_irq_config(ab);
 	if (ret)
-		return ret;
+		goto err_irq_affinity_cleanup;
 
 	return 0;
+
+err_irq_affinity_cleanup:
+	ath11k_pci_set_irq_affinity_hint(ab_pci, NULL);
+	return ret;
 }
 
 static void ath11k_pci_init_qmi_ce_config(struct ath11k_base *ab)
@@ -1488,6 +1507,8 @@ static void ath11k_pci_remove(struct pci_dev *pdev)
 	struct ath11k_base *ab = pci_get_drvdata(pdev);
 	struct ath11k_pci *ab_pci = ath11k_pci_priv(ab);
 
+	ath11k_pci_set_irq_affinity_hint(ab_pci, NULL);
+
 	if (test_bit(ATH11K_FLAG_QMI_FAIL, &ab->dev_flags)) {
 		ath11k_pci_power_down(ab);
 		ath11k_debugfs_soc_destroy(ab);