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Subject[PATCH 3/4] AHCI: Request multiple MSIs
Date
AHCI controllers can support up to 16 interrupts, one per port.  This
saves us a readl() in the interrupt path to determine which port has
generated the interrupt.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
---
drivers/ata/ahci.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 79 insertions(+), 5 deletions(-)
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 061817a..4b2f90a 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -102,6 +102,7 @@ enum {
/* HOST_CTL bits */
HOST_RESET = (1 << 0), /* reset controller; self-clear */
HOST_IRQ_EN = (1 << 1), /* global IRQ enable */
+ HOST_MSI_RSM = (1 << 2), /* Revert to Single Message */
HOST_AHCI_EN = (1 << 31), /* AHCI enabled */

/* HOST_CAP bits */
@@ -1771,6 +1772,13 @@ static void ahci_port_intr(struct ata_port *ap)
}
}

+static irqreturn_t ahci_msi_interrupt(int irq, void *dev_instance)
+{
+ struct ata_port *ap = dev_instance;
+ ahci_port_intr(ap);
+ return IRQ_HANDLED;
+}
+
static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
{
struct ata_host *host = dev_instance;
@@ -2210,6 +2218,66 @@ static void ahci_p5wdh_workaround(struct ata_host *host)
}
}

+static int ahci_request_irqs(struct pci_dev *pdev, struct ata_host *host)
+{
+ int i, n_irqs, rc;
+ struct ahci_host_priv *hpriv = host->private_data;
+
+ if (hpriv->flags & AHCI_HFLAG_NO_MSI) {
+ n_irqs = 1;
+ } else {
+ u16 control;
+ int pos = pci_find_capability(pdev, PCI_CAP_ID_MSI);
+ pci_read_config_word(pdev, pos + PCI_MSI_FLAGS, &control);
+ n_irqs = 1 << ((control & PCI_MSI_FLAGS_QMASK) >> 1);
+
+ for (;;) {
+ rc = pci_enable_msi_block(pdev, n_irqs);
+ if (rc == 0) {
+ void __iomem *mmio = host->iomap[AHCI_PCI_BAR];
+ u32 host_ctl = readl(mmio + HOST_CTL);
+ if ((host_ctl & HOST_MSI_RSM) == 0)
+ break;
+ pci_disable_msi(pdev);
+ n_irqs = 1;
+ } else if (rc < 0) {
+ n_irqs = 1;
+ pci_intx(pdev, 1);
+ break;
+ } else {
+ n_irqs = rc;
+ }
+ }
+ }
+
+ /* FIXME: Add support for CCC */
+ if (n_irqs > host->n_ports) {
+ n_irqs = host->n_ports;
+ } else if (n_irqs < host->n_ports) {
+ n_irqs--;
+ rc = devm_request_irq(host->dev, pdev->irq + n_irqs,
+ ahci_interrupt, IRQF_SHARED,
+ dev_driver_string(host->dev), host);
+ if (rc)
+ goto release_block;
+ }
+
+ for (i = 0; i < n_irqs; i++) {
+ rc = devm_request_irq(host->dev, pdev->irq + i,
+ ahci_msi_interrupt, IRQF_SHARED,
+ dev_driver_string(host->dev), host->ports[i]);
+ if (rc)
+ goto release_block;
+ }
+
+ return 0;
+
+ release_block:
+ pci_disable_msi(pdev);
+ pci_intx(pdev, 1);
+ return rc;
+}
+
static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
{
static int printed_version;
@@ -2268,9 +2336,6 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
(pdev->revision == 0xa1 || pdev->revision == 0xa2))
hpriv->flags |= AHCI_HFLAG_NO_MSI;

- if ((hpriv->flags & AHCI_HFLAG_NO_MSI) || pci_enable_msi(pdev))
- pci_intx(pdev, 1);
-
/* save initial config */
ahci_save_initial_config(pdev, hpriv);

@@ -2325,8 +2390,17 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
ahci_print_info(host);

pci_set_master(pdev);
- return ata_host_activate(host, pdev->irq, ahci_interrupt, IRQF_SHARED,
- &ahci_sht);
+
+ rc = ata_host_start(host);
+ if (rc)
+ return rc;
+
+ rc = ahci_request_irqs(pdev, host);
+ if (rc)
+ return rc;
+
+ rc = ata_host_register(host, &ahci_sht);
+ return rc;
}

static int __init ahci_init(void)
--
1.5.5.4


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