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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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