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@xxxxxxxxxx>
Suggested-by: "Jiang, Dave" <dave.jiang@xxxxxxxxx>
Cc: "Jiang, Dave" <dave.jiang@xxxxxxxxx>
Cc: linux-ide@xxxxxxxxxxxxxxx
---
drivers/ata/ahci.h | 2 +-
drivers/ata/libahci.c | 67 ++++++---------------------------------------------
2 files changed, 9 insertions(+), 60 deletions(-)
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 6a22055..40f0e34 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -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 */
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 48175e5..97683e4 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -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;
- 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);
+ status = readl(port_mmio + PORT_IRQ_STAT);
+ writel(status, port_mmio + PORT_IRQ_STAT);
- spin_unlock(&host->lock);
+ atomic_or(status, &pp->intr_status);
VPRINTK("EXIT\n");
--
1.8.3.1
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