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Commit 227dfb4d authored by Alexander Gordeev's avatar Alexander Gordeev Committed by Tejun Heo
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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: default avatarAlexander Gordeev <agordeev@redhat.com>
Suggested-by: default avatar"Jiang, Dave" <dave.jiang@intel.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: "Jiang, Dave" <dave.jiang@intel.com>
Cc: linux-ide@vger.kernel.org
parent 5ee1cfd9

drivers/ata/ahci.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -304,7 +304,7 @@ struct ahci_port_priv { 
	unsigned int		ncq_saw_d2h:1;

	unsigned int		ncq_saw_d2h:1;

	unsigned int		ncq_saw_dmas:1;

	unsigned int		ncq_saw_dmas:1;

	unsigned int		ncq_saw_sdb: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 */

	spinlock_t		lock;		/* protects parent ata_port */

	u32 			intr_mask;	/* interrupts to enable */

	u32 			intr_mask;	/* interrupts to enable */

	bool			fbs_supported;	/* set iff FBS is supported */

	bool			fbs_supported;	/* set iff FBS is supported */

drivers/ata/libahci.c

+8 −59
Original line number Original line Diff line number Diff line
@@ -1794,14 +1794,11 @@ static irqreturn_t ahci_port_thread_fn(int irq, void *dev_instance) 
	struct ata_port *ap = dev_instance;

	struct ata_port *ap = dev_instance;

	struct ahci_port_priv *pp = ap->private_data;

	struct ahci_port_priv *pp = ap->private_data;

	void __iomem *port_mmio = ahci_port_base(ap);

	void __iomem *port_mmio = ahci_port_base(ap);

	unsigned long flags;

	u32 status;

	u32 status;





	spin_lock_irqsave(&ap->host->lock, flags);

	status = atomic_xchg(&pp->intr_status, 0);

	status = pp->intr_status;

	if (!status)

	if (status)

		return IRQ_NONE;

		pp->intr_status = 0;

	spin_unlock_irqrestore(&ap->host->lock, flags);





	spin_lock_bh(ap->lock);

	spin_lock_bh(ap->lock);

	ahci_handle_port_interrupt(ap, port_mmio, status);

	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;

	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);

	void __iomem *port_mmio = ahci_port_base(ap);

	struct ahci_port_priv *pp = ap->private_data;

	struct ahci_port_priv *pp = ap->private_data;

	u32 status;

	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");

	VPRINTK("ENTER\n");





	spin_lock(&host->lock);

	status = readl(port_mmio + PORT_IRQ_STAT);



	writel(status, port_mmio + PORT_IRQ_STAT);

	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");

	VPRINTK("EXIT\n");