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 | 59 +++++++++++----------------------------------------
2 files changed, 13 insertions(+), 47 deletions(-)
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 6a22055..e5c6048 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 48175e5..fafa7f0 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1797,11 +1797,14 @@ static 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);
+
+ if (!status)
+ return IRQ_NONE;
spin_lock_bh(ap->lock);
ahci_handle_port_interrupt(ap, port_mmio, status);
@@ -1824,53 +1827,14 @@ 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_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");
@@ -2349,7 +2313,8 @@ static int ahci_port_start(struct ata_port *ap)
/*
* Switch to per-port locking in case each port has its own MSI vector.
*/
- if ((hpriv->flags & AHCI_HFLAG_MULTI_MSI)) {
+ if (hpriv->flags & AHCI_HFLAG_MULTI_MSI) {
+ spin_lock_init(&pp->intr_lock);
spin_lock_init(&pp->lock);
ap->lock = &pp->lock;
}
--
1.8.3.1
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