5 files changed, 50 insertions, 20 deletions

diff --git a/drivers/accel/qaic/mhi_controller.c b/drivers/accel/qaic/mhi_controller.c
index 5036e58e7235..41be3626587d 100644
--- a/drivers/accel/qaic/mhi_controller.c
+++ b/drivers/accel/qaic/mhi_controller.c
@@ -468,7 +468,7 @@ static int mhi_reset_and_async_power_up(struct mhi_controller *mhi_cntrl)
 }
 
 struct mhi_controller *qaic_mhi_register_controller(struct pci_dev *pci_dev, void __iomem *mhi_bar,
-						    int mhi_irq)
+						    int mhi_irq, bool shared_msi)
 {
 	struct mhi_controller *mhi_cntrl;
 	int ret;
@@ -500,6 +500,10 @@ struct mhi_controller *qaic_mhi_register_controller(struct pci_dev *pci_dev, voi
 		return ERR_PTR(-ENOMEM);
 
 	mhi_cntrl->irq[0] = mhi_irq;
+
+	if (shared_msi) /* MSI shared with data path, no IRQF_NO_SUSPEND */
+		mhi_cntrl->irq_flags = IRQF_SHARED;
+
 	mhi_cntrl->fw_image = "qcom/aic100/sbl.bin";
 
 	/* use latest configured timeout */
diff --git a/drivers/accel/qaic/mhi_controller.h b/drivers/accel/qaic/mhi_controller.h
index 2ae45d768e24..500e7f4af2af 100644
--- a/drivers/accel/qaic/mhi_controller.h
+++ b/drivers/accel/qaic/mhi_controller.h
@@ -8,7 +8,7 @@
 #define MHICONTROLLERQAIC_H_
 
 struct mhi_controller *qaic_mhi_register_controller(struct pci_dev *pci_dev, void __iomem *mhi_bar,
-						    int mhi_irq);
+						    int mhi_irq, bool shared_msi);
 void qaic_mhi_free_controller(struct mhi_controller *mhi_cntrl, bool link_up);
 void qaic_mhi_start_reset(struct mhi_controller *mhi_cntrl);
 void qaic_mhi_reset_done(struct mhi_controller *mhi_cntrl);
diff --git a/drivers/accel/qaic/qaic.h b/drivers/accel/qaic/qaic.h
index e3f4c30f3ffd..01e9dda0cc37 100644
--- a/drivers/accel/qaic/qaic.h
+++ b/drivers/accel/qaic/qaic.h
@@ -123,6 +123,8 @@ struct qaic_device {
 	struct srcu_struct	dev_lock;
 	/* true: Device under reset; false: Device not under reset */
 	bool			in_reset;
+	/* true: single MSI is used to operate device */
+	bool			single_msi;
 	/*
 	 * true: A tx MHI transaction has failed and a rx buffer is still queued
 	 * in control device. Such a buffer is considered lost rx buffer
diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
index 4a8e43a7a6a4..ebc3cca1b094 100644
--- a/drivers/accel/qaic/qaic_data.c
+++ b/drivers/accel/qaic/qaic_data.c
@@ -1466,6 +1466,16 @@ irqreturn_t dbc_irq_handler(int irq, void *data)
 
 	rcu_id = srcu_read_lock(&dbc->ch_lock);
 
+	if (datapath_polling) {
+		srcu_read_unlock(&dbc->ch_lock, rcu_id);
+		/*
+		 * Normally datapath_polling will not have irqs enabled, but
+		 * when running with only one MSI the interrupt is shared with
+		 * MHI so it cannot be disabled. Return ASAP instead.
+		 */
+		return IRQ_HANDLED;
+	}
+
 	if (!dbc->usr) {
 		srcu_read_unlock(&dbc->ch_lock, rcu_id);
 		return IRQ_HANDLED;
@@ -1488,7 +1498,8 @@ irqreturn_t dbc_irq_handler(int irq, void *data)
 		return IRQ_NONE;
 	}
 
-	disable_irq_nosync(irq);
+	if (!dbc->qdev->single_msi)
+		disable_irq_nosync(irq);
 	srcu_read_unlock(&dbc->ch_lock, rcu_id);
 	return IRQ_WAKE_THREAD;
 }
@@ -1559,12 +1570,12 @@ irqreturn_t dbc_irq_threaded_fn(int irq, void *data)
 	u32 tail;
 
 	rcu_id = srcu_read_lock(&dbc->ch_lock);
+	qdev = dbc->qdev;
 
 	head = readl(dbc->dbc_base + RSPHP_OFF);
 	if (head == U32_MAX) /* PCI link error */
 		goto error_out;
 
-	qdev = dbc->qdev;
 read_fifo:
 
 	if (!event_count) {
@@ -1645,14 +1656,14 @@ read_fifo:
 	goto read_fifo;
 
 normal_out:
-	if (likely(!datapath_polling))
+	if (!qdev->single_msi && likely(!datapath_polling))
 		enable_irq(irq);
-	else
+	else if (unlikely(datapath_polling))
 		schedule_work(&dbc->poll_work);
 	/* checking the fifo and enabling irqs is a race, missed event check */
 	tail = readl(dbc->dbc_base + RSPTP_OFF);
 	if (tail != U32_MAX && head != tail) {
-		if (likely(!datapath_polling))
+		if (!qdev->single_msi && likely(!datapath_polling))
 			disable_irq_nosync(irq);
 		goto read_fifo;
 	}
@@ -1661,9 +1672,9 @@ normal_out:
 
 error_out:
 	srcu_read_unlock(&dbc->ch_lock, rcu_id);
-	if (likely(!datapath_polling))
+	if (!qdev->single_msi && likely(!datapath_polling))
 		enable_irq(irq);
-	else
+	else if (unlikely(datapath_polling))
 		schedule_work(&dbc->poll_work);
 
 	return IRQ_HANDLED;
diff --git a/drivers/accel/qaic/qaic_drv.c b/drivers/accel/qaic/qaic_drv.c
index 6f58095767df..5eba5f03d3bf 100644
--- a/drivers/accel/qaic/qaic_drv.c
+++ b/drivers/accel/qaic/qaic_drv.c
@@ -424,14 +424,24 @@ static int init_msi(struct qaic_device *qdev, struct pci_dev *pdev)
 	int i;
 
 	/* Managed release since we use pcim_enable_device */
-	ret = pci_alloc_irq_vectors(pdev, 1, 32, PCI_IRQ_MSI);
-	if (ret < 0)
-		return ret;
+	ret = pci_alloc_irq_vectors(pdev, 32, 32, PCI_IRQ_MSI);
+	if (ret == -ENOSPC) {
+		ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
+		if (ret < 0)
+			return ret;
 
-	if (ret < 32) {
-		pci_err(pdev, "%s: Requested 32 MSIs. Obtained %d MSIs which is less than the 32 required.\n",
-			__func__, ret);
-		return -ENODEV;
+		/*
+		 * Operate in one MSI mode. All interrupts will be directed to
+		 * MSI0; every interrupt will wake up all the interrupt handlers
+		 * (MHI and DBC[0-15]). Since the interrupt is now shared, it is
+		 * not disabled during DBC threaded handler, but only one thread
+		 * will be allowed to run per DBC, so while it can be
+		 * interrupted, it shouldn't race with itself.
+		 */
+		qdev->single_msi = true;
+		pci_info(pdev, "Allocating 32 MSIs failed, operating in 1 MSI mode. Performance may be impacted.\n");
+	} else if (ret < 0) {
+		return ret;
 	}
 
 	mhi_irq = pci_irq_vector(pdev, 0);
@@ -439,15 +449,17 @@ static int init_msi(struct qaic_device *qdev, struct pci_dev *pdev)
 		return mhi_irq;
 
 	for (i = 0; i < qdev->num_dbc; ++i) {
-		ret = devm_request_threaded_irq(&pdev->dev, pci_irq_vector(pdev, i + 1),
+		ret = devm_request_threaded_irq(&pdev->dev,
+						pci_irq_vector(pdev, qdev->single_msi ? 0 : i + 1),
 						dbc_irq_handler, dbc_irq_threaded_fn, IRQF_SHARED,
 						"qaic_dbc", &qdev->dbc[i]);
 		if (ret)
 			return ret;
 
 		if (datapath_polling) {
-			qdev->dbc[i].irq = pci_irq_vector(pdev, i + 1);
-			disable_irq_nosync(qdev->dbc[i].irq);
+			qdev->dbc[i].irq = pci_irq_vector(pdev, qdev->single_msi ? 0 : i + 1);
+			if (!qdev->single_msi)
+				disable_irq_nosync(qdev->dbc[i].irq);
 			INIT_WORK(&qdev->dbc[i].poll_work, irq_polling_work);
 		}
 	}
@@ -479,7 +491,8 @@ static int qaic_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto cleanup_qdev;
 	}
 
-	qdev->mhi_cntrl = qaic_mhi_register_controller(pdev, qdev->bar_0, mhi_irq);
+	qdev->mhi_cntrl = qaic_mhi_register_controller(pdev, qdev->bar_0, mhi_irq,
+						       qdev->single_msi);
 	if (IS_ERR(qdev->mhi_cntrl)) {
 		ret = PTR_ERR(qdev->mhi_cntrl);
 		goto cleanup_qdev;