From 227dfb4dbf109596d76a9b842856c4ff68e4efb2 Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Mon, 29 Sep 2014 18:26:01 +0200 Subject: [PATCH] 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 Suggested-by: "Jiang, Dave" Signed-off-by: Tejun Heo Cc: "Jiang, Dave" Cc: linux-ide@vger.kernel.org --- 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 6a22055151f0..40f0e34f17af 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 48175e5bd001..97683e45ab04 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"); -- 2.20.1