Commit 4cfd2188 authored by Heiner Kallweit's avatar Heiner Kallweit Committed by David S. Miller
Browse files

PCI: let pci_disable_link_state propagate errors 



Drivers may rely on pci_disable_link_state() having disabled certain
ASPM link states. If OS can't control ASPM then pci_disable_link_state()
turns into a no-op w/o informing the caller. The driver therefore may
falsely assume the respective ASPM link states are disabled.
Let pci_disable_link_state() propagate errors to the caller, enabling
the caller to react accordingly.

Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dca73a65

drivers/pci/pcie/aspm.c

+11 −9
Original line number Diff line number Diff line
@@ -1062,18 +1062,18 @@ void pcie_aspm_powersave_config_link(struct pci_dev *pdev) 
	up_read(&pci_bus_sem);

}



static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)

static int __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)

{

	struct pci_dev *parent = pdev->bus->self;

	struct pcie_link_state *link;



	if (!pci_is_pcie(pdev))

		return;

		return 0;



	if (pdev->has_secondary_link)

		parent = pdev;

	if (!parent || !parent->link_state)

		return;

		return -EINVAL;



	/*

	 * A driver requested that ASPM be disabled on this device, but
@@ -1085,7 +1085,7 @@ static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem) 
	 */

	if (aspm_disabled) {

		pci_warn(pdev, "can't disable ASPM; OS doesn't have ASPM control\n");

		return;

		return -EPERM;

	}



	if (sem)
@@ -1105,11 +1105,13 @@ static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem) 
	mutex_unlock(&aspm_lock);

	if (sem)

		up_read(&pci_bus_sem);



	return 0;

}



void pci_disable_link_state_locked(struct pci_dev *pdev, int state)

int pci_disable_link_state_locked(struct pci_dev *pdev, int state)

{

	__pci_disable_link_state(pdev, state, false);

	return __pci_disable_link_state(pdev, state, false);

}

EXPORT_SYMBOL(pci_disable_link_state_locked);
@@ -1117,14 +1119,14 @@ EXPORT_SYMBOL(pci_disable_link_state_locked); 
 * pci_disable_link_state - Disable device's link state, so the link will

 * never enter specific states.  Note that if the BIOS didn't grant ASPM

 * control to the OS, this does nothing because we can't touch the LNKCTL

 * register.

 * register. Returns 0 or a negative errno.

 *

 * @pdev: PCI device

 * @state: ASPM link state to disable

 */

void pci_disable_link_state(struct pci_dev *pdev, int state)

int pci_disable_link_state(struct pci_dev *pdev, int state)

{

	__pci_disable_link_state(pdev, state, true);

	return __pci_disable_link_state(pdev, state, true);

}

EXPORT_SYMBOL(pci_disable_link_state);

include/linux/pci-aspm.h

+4 −3
Original line number Diff line number Diff line
@@ -24,11 +24,12 @@ 
#define PCIE_LINK_STATE_CLKPM	4



#ifdef CONFIG_PCIEASPM

void pci_disable_link_state(struct pci_dev *pdev, int state);

void pci_disable_link_state_locked(struct pci_dev *pdev, int state);

int pci_disable_link_state(struct pci_dev *pdev, int state);

int pci_disable_link_state_locked(struct pci_dev *pdev, int state);

void pcie_no_aspm(void);

#else

static inline void pci_disable_link_state(struct pci_dev *pdev, int state) { }

static inline int pci_disable_link_state(struct pci_dev *pdev, int state)

{ return 0; }

static inline void pcie_no_aspm(void) { }

#endif

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