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Subject[PATCH RFC 08/77] PCI/MSI: Get rid of pci_enable_msi_block_auto() interface
As result of recent re-design of MSI/MSI-X interrupts enabling
pattern pci_enable_msi_block_auto() interface became obsolete.

To enable maximum number of MSI interrupts for a device the
driver will first obtain that number from pci_get_msi_cap()
function and then call pci_enable_msi_block() interface.

Signed-off-by: Alexander Gordeev <>
Documentation/PCI/MSI-HOWTO.txt | 30 ++----------------------------
drivers/pci/msi.c | 20 --------------------
include/linux/pci.h | 7 -------
3 files changed, 2 insertions(+), 55 deletions(-)

diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index 40abcfb..4d0525f 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -133,33 +133,7 @@ static int foo_driver_enable_msi(struct foo_adapter *adapter, int nvec)
return rc;

-4.2.3 pci_enable_msi_block_auto
-int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *count)
-This variation on pci_enable_msi() call allows a device driver to request
-the maximum possible number of MSIs. The MSI specification only allows
-interrupts to be allocated in powers of two, up to a maximum of 2^5 (32).
-If this function returns a positive number, it indicates that it has
-succeeded and the returned value is the number of allocated interrupts. In
-this case, the function enables MSI on this device and updates dev->irq to
-be the lowest of the new interrupts assigned to it. The other interrupts
-assigned to the device are in the range dev->irq to dev->irq + returned
-value - 1.
-If this function returns a negative number, it indicates an error and
-the driver should not attempt to request any more MSI interrupts for
-this device.
-If the device driver needs to know the number of interrupts the device
-supports it can pass the pointer count where that number is stored. The
-device driver must decide what action to take if pci_enable_msi_block_auto()
-succeeds, but returns a value less than the number of interrupts supported.
-If the device driver does not need to know the number of interrupts
-supported, it can set the pointer count to NULL.
-4.2.4 pci_disable_msi
+4.2.3 pci_disable_msi

void pci_disable_msi(struct pci_dev *dev)

@@ -175,7 +149,7 @@ on any interrupt for which it previously called request_irq().
Failure to do so results in a BUG_ON(), leaving the device with
MSI enabled and thus leaking its vector.

-4.2.5 pci_get_msi_cap
+4.2.4 pci_get_msi_cap

int pci_get_msi_cap(struct pci_dev *dev)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 583ace1..1934519 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -849,26 +849,6 @@ int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)

-int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
- int ret, nvec;
- ret = pci_get_msi_cap(dev);
- if (ret < 0)
- return ret;
- if (maxvec)
- *maxvec = ret;
- nvec = ret;
- ret = pci_enable_msi_block(dev, nvec);
- if (ret)
- return ret;
- return nvec;
void pci_msi_shutdown(struct pci_dev *dev)
struct msi_desc *desc;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2fa92ef..13bf88d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1154,12 +1154,6 @@ static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)
return -1;

-static inline int
-pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
- return -1;
static inline void pci_msi_shutdown(struct pci_dev *dev)
{ }
static inline void pci_disable_msi(struct pci_dev *dev)
@@ -1192,7 +1186,6 @@ static inline int pci_msi_enabled(void)
int pci_get_msi_cap(struct pci_dev *dev);
int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec);
-int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec);
void pci_msi_shutdown(struct pci_dev *dev);
void pci_disable_msi(struct pci_dev *dev);
int pci_msix_table_size(struct pci_dev *dev);

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