On Fri, Sep 19, 2014 at 09:25:52AM +0100, Alexander Gordeev wrote:
> As described in AHCI v1.0 specification chapter 10.6.2.2
> "Multiple MSI Based Messages" generation of interrupts
> is not controlled through the HOST_IRQ_STAT register.
>
> Considering MMIO access is expensive remove unnecessary
> reading and writing of HOST_IRQ_STAT register.
>
> Further, serializing access to the host data is no longer
> needed and the interrupt service routine can avoid competing
> on the host lock.
>
> Signed-off-by: Alexander Gordeev <agord...@redhat.com>
> Suggested-by: "Jiang, Dave" <dave.ji...@intel.com>
> Cc: linux-...@vger.kernel.org
> ---
> drivers/ata/ahci.h | 1 +
> drivers/ata/libahci.c | 54
> ++++++++-------------------------------------------
> 2 files changed, 9 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
> index c12f590..b8e117a 100644
> --- a/drivers/ata/ahci.h
> +++ b/drivers/ata/ahci.h
> @@ -305,6 +305,7 @@ struct ahci_port_priv {
> unsigned int ncq_saw_dmas:1;
> unsigned int ncq_saw_sdb:1;
> u32 intr_status; /* interrupts to handle */
> + spinlock_t intr_lock; /* protects intr_status */
> spinlock_t lock; /* protects parent ata_port */
> u32 intr_mask; /* interrupts to enable */
> bool fbs_supported; /* set iff FBS is supported */
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 169c272..b9c4e93 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -1785,11 +1785,11 @@ irqreturn_t ahci_port_thread_fn(int irq, void
> *dev_instance)
> unsigned long flags;
> u32 status;
>
> - spin_lock_irqsave(&ap->host->lock, flags);
> + spin_lock_irqsave(&pp->intr_lock, flags);
> status = pp->intr_status;
> if (status)
> pp->intr_status = 0;
> - spin_unlock_irqrestore(&ap->host->lock, flags);
> + spin_unlock_irqrestore(&pp->intr_lock, flags);
This change ^^^ is wrong in single interrupt mode.
Self-Nack.
> spin_lock_bh(ap->lock);
> ahci_handle_port_interrupt(ap, status);
> @@ -1842,53 +1842,14 @@ static void ahci_update_intr_status(struct ata_port
> *ap)
>
> irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
> {
> - struct ata_port *ap_this = dev_instance;
> - struct ahci_port_priv *pp = ap_this->private_data;
> - struct ata_host *host = ap_this->host;
> - struct ahci_host_priv *hpriv = host->private_data;
> - void __iomem *mmio = hpriv->mmio;
> - unsigned int i;
> - u32 irq_stat, irq_masked;
> + struct ata_port *ap = dev_instance;
> + struct ahci_port_priv *pp = ap->private_data;
>
> VPRINTK("ENTER\n");
>
> - spin_lock(&host->lock);
> -
> - irq_stat = readl(mmio + HOST_IRQ_STAT);
> -
> - if (!irq_stat) {
> - u32 status = pp->intr_status;
> -
> - spin_unlock(&host->lock);
> -
> - VPRINTK("EXIT\n");
> -
> - return status ? IRQ_WAKE_THREAD : IRQ_NONE;
> - }
> -
> - irq_masked = irq_stat & hpriv->port_map;
> -
> - for (i = 0; i < host->n_ports; i++) {
> - struct ata_port *ap;
> -
> - if (!(irq_masked & (1 << i)))
> - continue;
> -
> - ap = host->ports[i];
> - if (ap) {
> - ahci_update_intr_status(ap);
> - VPRINTK("port %u\n", i);
> - } else {
> - VPRINTK("port %u (no irq)\n", i);
> - if (ata_ratelimit())
> - dev_warn(host->dev,
> - "interrupt on disabled port %u\n", i);
> - }
> - }
> -
> - writel(irq_stat, mmio + HOST_IRQ_STAT);
> -
> - spin_unlock(&host->lock);
> + spin_lock(&pp->intr_lock);
> + ahci_update_intr_status(ap);
> + spin_unlock(&pp->intr_lock);
>
> VPRINTK("EXIT\n");
>
> @@ -2366,6 +2327,7 @@ static int ahci_port_start(struct ata_port *ap)
> */
> pp->intr_mask = DEF_PORT_IRQ;
>
> + spin_lock_init(&pp->intr_lock);
> spin_lock_init(&pp->lock);
> ap->lock = &pp->lock;
>
> --
> 1.8.3.1
>
> --
> Regards,
> Alexander Gordeev
> agord...@redhat.com
--
Regards,
Alexander Gordeev
agord...@redhat.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
