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Commit b48d4425 authored by Jesse Barnes's avatar Jesse Barnes
Browse files

PCI: add ID-based ordering enable/disable support 



Add support to allow drivers to enable/disable ID-based ordering.  Where
supported, ID-based ordering can significantly improve the latency of
individual requests by preventing them from queueing up behind unrelated
traffic.

Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent 69643e48

drivers/pci/pci.c

+53 −0
Original line number Diff line number Diff line
@@ -1834,6 +1834,59 @@ void pci_enable_ari(struct pci_dev *dev) 
	bridge->ari_enabled = 1;

}



/**

 * pci_enable_ido - enable ID-based ordering on a device

 * @dev: the PCI device

 * @type: which types of IDO to enable

 *

 * Enable ID-based ordering on @dev.  @type can contain the bits

 * %PCI_EXP_IDO_REQUEST and/or %PCI_EXP_IDO_COMPLETION to indicate

 * which types of transactions are allowed to be re-ordered.

 */

void pci_enable_ido(struct pci_dev *dev, unsigned long type)

{

	int pos;

	u16 ctrl;



	pos = pci_pcie_cap(dev);

	if (!pos)

		return;



	pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);

	if (type & PCI_EXP_IDO_REQUEST)

		ctrl |= PCI_EXP_IDO_REQ_EN;

	if (type & PCI_EXP_IDO_COMPLETION)

		ctrl |= PCI_EXP_IDO_CMP_EN;

	pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl);

}

EXPORT_SYMBOL(pci_enable_ido);



/**

 * pci_disable_ido - disable ID-based ordering on a device

 * @dev: the PCI device

 * @type: which types of IDO to disable

 */

void pci_disable_ido(struct pci_dev *dev, unsigned long type)

{

	int pos;

	u16 ctrl;



	if (!pci_is_pcie(dev))

		return;



	pos = pci_pcie_cap(dev);

	if (!pos)

		return;



	pci_read_config_word(dev, pos + PCI_EXP_DEVCTL2, &ctrl);

	if (type & PCI_EXP_IDO_REQUEST)

		ctrl &= ~PCI_EXP_IDO_REQ_EN;

	if (type & PCI_EXP_IDO_COMPLETION)

		ctrl &= ~PCI_EXP_IDO_CMP_EN;

	pci_write_config_word(dev, pos + PCI_EXP_DEVCTL2, ctrl);

}

EXPORT_SYMBOL(pci_disable_ido);



static int pci_acs_enable;



/**

include/linux/pci.h

+13 −0
Original line number Diff line number Diff line
@@ -828,6 +828,11 @@ static inline int pci_enable_wake(struct pci_dev *dev, pci_power_t state, 
	return __pci_enable_wake(dev, state, false, enable);

}



#define PCI_EXP_IDO_REQUEST	(1<<0)

#define PCI_EXP_IDO_COMPLETION	(1<<1)

void pci_enable_ido(struct pci_dev *dev, unsigned long type);

void pci_disable_ido(struct pci_dev *dev, unsigned long type);



/* For use by arch with custom probe code */

void set_pcie_port_type(struct pci_dev *pdev);

void set_pcie_hotplug_bridge(struct pci_dev *pdev);
@@ -1207,6 +1212,14 @@ static inline int pci_enable_wake(struct pci_dev *dev, pci_power_t state, 
	return 0;

}



static inline void pci_enable_ido(struct pci_dev *dev, unsigned long type)

{

}



static inline void pci_disable_ido(struct pci_dev *dev, unsigned long type)

{

}



static inline int pci_request_regions(struct pci_dev *dev, const char *res_name)

{

	return -EIO;

include/linux/pci_regs.h

+2 −0
Original line number Diff line number Diff line
@@ -510,6 +510,8 @@ 
#define  PCI_EXP_DEVCAP2_ARI	0x20	/* Alternative Routing-ID */

#define PCI_EXP_DEVCTL2		40	/* Device Control 2 */

#define  PCI_EXP_DEVCTL2_ARI	0x20	/* Alternative Routing-ID */

#define  PCI_EXP_IDO_REQ_EN	0x100	/* ID-based ordering request enable */

#define  PCI_EXP_IDO_CMP_EN	0x200	/* ID-based ordering completion enable */

#define PCI_EXP_LNKCTL2		48	/* Link Control 2 */

#define PCI_EXP_SLTCTL2		56	/* Slot Control 2 */