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AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode 

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 <agordeev@redhat.com>
Suggested-by: "Jiang, Dave" <dave.jiang@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "Jiang, Dave" <dave.jiang@intel.com>
Cc: linux-ide@vger.kernel.org
This commit is contained in:
Alexander Gordeev 2014-09-29 18:26:01 +02:00 committed by Tejun Heo
parent 5ee1cfd975
commit 227dfb4dbf
2 changed files with 9 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/ata/ahci.h
View File

@ -304,7 +304,7 @@ struct ahci_port_priv {
unsigned int ncq_saw_d2h:1;
unsigned int ncq_saw_dmas:1;
unsigned int ncq_saw_sdb:1;
u32 intr_status; /* interrupts to handle */
atomic_t intr_status; /* interrupts to handle */
spinlock_t lock; /* protects parent ata_port */
u32 intr_mask; /* interrupts to enable */
bool fbs_supported; /* set iff FBS is supported */

67
drivers/ata/libahci.c
View File

@ -1794,14 +1794,11 @@ static irqreturn_t ahci_port_thread_fn(int irq, void *dev_instance)
struct ata_port *ap = dev_instance;
struct ahci_port_priv *pp = ap->private_data;
void __iomem *port_mmio = ahci_port_base(ap);
unsigned long flags;
u32 status;
spin_lock_irqsave(&ap->host->lock, flags);
status = pp->intr_status;
if (status)
pp->intr_status = 0;
spin_unlock_irqrestore(&ap->host->lock, flags);
status = atomic_xchg(&pp->intr_status, 0);
if (!status)
return IRQ_NONE;
spin_lock_bh(ap->lock);
ahci_handle_port_interrupt(ap, port_mmio, status);
@ -1810,67 +1807,19 @@ static irqreturn_t ahci_port_thread_fn(int irq, void *dev_instance)
return IRQ_HANDLED;
}
static void ahci_update_intr_status(struct ata_port *ap)
static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
{
struct ata_port *ap = dev_instance;
void __iomem *port_mmio = ahci_port_base(ap);
struct ahci_port_priv *pp = ap->private_data;
u32 status;
VPRINTK("ENTER\n");
status = readl(port_mmio + PORT_IRQ_STAT);
writel(status, port_mmio + PORT_IRQ_STAT);
pp->intr_status |= status;
}
static 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;
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);
atomic_or(status, &pp->intr_status);
VPRINTK("EXIT\n");