ath11k: pci: support platforms with one MSI vector

Dell XPS 13 9310 has only one MSI vector available for QCA6390 device and ath11k fails with:

ath11k_pci 0000:56:00.0: failed to get 32 MSI vectors, only -28 available
ath11k_pci 0000:56:00.0: failed to enable msi: -28
ath11k_pci: probe of 0000:56:00.0 failed with error -28

This is a proof of concept patch for getting ath11k to work with QCA6390 using
only one MSI vector, not the final solution. Testing feedback more than
welcome. The patch applies to v5.10-rc2.

The idea here is to add a flag to indicate whether this ISR can be called
or not as all the ISR handlers are registered with IRQF_SHARED when ath11k can
only request 1 vector. This needs to be refined later.

In some scenarios, kernel crashed when the interrupt migration happens, so add
IRQF_NOBALANCING.

Also add debug messages to ath11k_qmi_respond_fw_mem_request() for helping to
debug mysterious firmware initialisation timeouts:

ath11k_pci 0000:05:00.0: qmi failed memory request, err = -110
ath11k_pci 0000:05:00.0: qmi failed to respond fw mem req:-110

If that happens, one way to workaround the problem is to revert this commit:

7fef431 mm/page_alloc: place pages to tail in __free_pages_core()

Link: https://lore.kernel.org/linux-pci/87mtzxkus5.fsf@nanos.tec.linutronix.de/
Link: http://lists.infradead.org/pipermail/ath11k/2020-November/000550.html
Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/bus/mhi/core/init.c

@@ -153,7 +153,7 @@ int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl)
 	/* Setup BHI_INTVEC IRQ */
 	ret = request_threaded_irq(mhi_cntrl->irq[0], mhi_intvec_handler,
 				   mhi_intvec_threaded_handler,
-				   IRQF_SHARED | IRQF_NO_SUSPEND,
+				   IRQF_SHARED | IRQF_NOBALANCING,
 				   "bhi", mhi_cntrl);
 	if (ret)
 		return ret;
@@ -171,7 +171,7 @@ int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl)
 
 		ret = request_irq(mhi_cntrl->irq[mhi_event->irq],
 				  mhi_irq_handler,
-				  IRQF_SHARED | IRQF_NO_SUSPEND,
+				  IRQF_SHARED | IRQF_NOBALANCING,
 				  "mhi", mhi_event);
 		if (ret) {
 			dev_err(dev, "Error requesting irq:%d for ev:%d\n",

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

@@ -459,20 +459,22 @@ static void ath11k_ce_srng_msi_ring_params_setup(struct ath11k_base *ab, u32 ce_
 	u32 msi_irq_start;
 	u32 addr_lo;
 	u32 addr_hi;
+	u32 vectors_32_capability;
 	int ret;
 
 	ret = ath11k_get_user_msi_vector(ab, "CE",
 					 &msi_data_count, &msi_data_start,
 					 &msi_irq_start);
-
 	if (ret)
 		return;
+	vectors_32_capability = ab->hif.ops->is_32_vecs_support(ab);
 
 	ath11k_get_msi_address(ab, &addr_lo, &addr_hi);
 
 	ring_params->msi_addr = addr_lo;
 	ring_params->msi_addr |= (dma_addr_t)(((uint64_t)addr_hi) << 32);
-	ring_params->msi_data = (ce_id % msi_data_count) + msi_data_start;
+	ring_params->msi_data = vectors_32_capability ?
+		(ce_id % msi_data_count) + msi_data_start : msi_data_start;
 	ring_params->flags |= HAL_SRNG_FLAGS_MSI_INTR;
 }
 

drivers/net/wireless/ath/ath11k/core.h

@@ -683,6 +683,7 @@ struct ath11k_base {
 	bool wmi_ready;
 	u32 wlan_init_status;
 	int irq_num[ATH11K_IRQ_NUM_MAX];
+	int irq_enable_flag[ATH11K_IRQ_NUM_MAX];
 	struct ath11k_ext_irq_grp ext_irq_grp[ATH11K_EXT_IRQ_GRP_NUM_MAX];
 	struct napi_struct *napi;
 	struct ath11k_targ_cap target_caps;

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

@@ -180,13 +180,15 @@ static void ath11k_dp_srng_msi_setup(struct ath11k_base *ab,
 {
 	int msi_group_number, msi_data_count;
 	u32 msi_data_start, msi_irq_start, addr_lo, addr_hi;
-	int ret;
+	u32 vectors_32_capability;
+	int ret = -EINVAL;
 
 	ret = ath11k_get_user_msi_vector(ab, "DP",
 					 &msi_data_count, &msi_data_start,
 					 &msi_irq_start);
 	if (ret)
 		return;
+	vectors_32_capability = ab->hif.ops->is_32_vecs_support(ab);
 
 	msi_group_number = ath11k_dp_srng_calculate_msi_group(ab, type,
 							      ring_num);
@@ -209,8 +211,8 @@ static void ath11k_dp_srng_msi_setup(struct ath11k_base *ab,
 
 	ring_params->msi_addr = addr_lo;
 	ring_params->msi_addr |= (dma_addr_t)(((uint64_t)addr_hi) << 32);
-	ring_params->msi_data = (msi_group_number % msi_data_count)
-		+ msi_data_start;
+	ring_params->msi_data = vectors_32_capability ?
+		(msi_group_number % msi_data_count) + msi_data_start : msi_data_start;
 	ring_params->flags |= HAL_SRNG_FLAGS_MSI_INTR;
 }
 

drivers/net/wireless/ath/ath11k/hif.h

@@ -24,6 +24,7 @@ struct ath11k_hif_ops {
 				   u32 *base_vector);
 	void (*get_msi_address)(struct ath11k_base *ab, u32 *msi_addr_lo,
 				u32 *msi_addr_hi);
+	int (*is_32_vecs_support)(struct ath11k_base *ab);
 };
 
 static inline int ath11k_hif_start(struct ath11k_base *sc)

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

@@ -156,14 +156,17 @@ static int ath11k_mhi_get_msi(struct ath11k_pci *ab_pci)
 {
 	struct ath11k_base *ab = ab_pci->ab;
 	u32 user_base_data, base_vector;
+	u32 vectors_32_capability;
 	int ret, num_vectors, i;
 	int *irq;
+	unsigned int msi_data;
 
 	ret = ath11k_pci_get_user_msi_assignment(ab_pci,
 						 "MHI", &num_vectors,
 						 &user_base_data, &base_vector);
 	if (ret)
 		return ret;
+	vectors_32_capability = ab_pci->vectors_32_capability;
 
 	ath11k_dbg(ab, ATH11K_DBG_PCI, "Number of assigned MSI for MHI is %d, base vector is %d\n",
 		   num_vectors, base_vector);
@@ -172,9 +175,13 @@ static int ath11k_mhi_get_msi(struct ath11k_pci *ab_pci)
 	if (!irq)
 		return -ENOMEM;
 
-	for (i = 0; i < num_vectors; i++)
+	for (i = 0; i < num_vectors; i++) {
+		msi_data = vectors_32_capability ?
+			   i + base_vector : base_vector;
+
 		irq[i] = ath11k_pci_get_msi_irq(ab->dev,
-						base_vector + i);
+						msi_data);
+	}
 
 	ab_pci->mhi_ctrl->irq = irq;
 	ab_pci->mhi_ctrl->nr_irqs = num_vectors;