diff options
Diffstat (limited to 'Documentation/PCI/pci.rst')
| -rw-r--r-- | Documentation/PCI/pci.rst | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/Documentation/PCI/pci.rst b/Documentation/PCI/pci.rst index fa651e25d98c..f4d2662871ab 100644 --- a/Documentation/PCI/pci.rst +++ b/Documentation/PCI/pci.rst @@ -52,7 +52,7 @@ driver generally needs to perform the following initialization: - Enable DMA/processing engines When done using the device, and perhaps the module needs to be unloaded, -the driver needs to take the follow steps: +the driver needs to take the following steps: - Disable the device from generating IRQs - Release the IRQ (free_irq()) @@ -103,6 +103,7 @@ need pass only as many optional fields as necessary: - subvendor and subdevice fields default to PCI_ANY_ID (FFFFFFFF) - class and classmask fields default to 0 - driver_data defaults to 0UL. + - override_only field defaults to 0. Note that driver_data must match the value used by any of the pci_device_id entries defined in the driver. This makes the driver_data field mandatory @@ -272,25 +273,25 @@ Set the DMA mask size While all drivers should explicitly indicate the DMA capability (e.g. 32 or 64 bit) of the PCI bus master, devices with more than 32-bit bus master capability for streaming data need the driver -to "register" this capability by calling pci_set_dma_mask() with +to "register" this capability by calling dma_set_mask() with appropriate parameters. In general this allows more efficient DMA on systems where System RAM exists above 4G _physical_ address. Drivers for all PCI-X and PCIe compliant devices must call -pci_set_dma_mask() as they are 64-bit DMA devices. +dma_set_mask() as they are 64-bit DMA devices. Similarly, drivers must also "register" this capability if the device -can directly address "consistent memory" in System RAM above 4G physical -address by calling pci_set_consistent_dma_mask(). +can directly address "coherent memory" in System RAM above 4G physical +address by calling dma_set_coherent_mask(). Again, this includes drivers for all PCI-X and PCIe compliant devices. Many 64-bit "PCI" devices (before PCI-X) and some PCI-X devices are 64-bit DMA capable for payload ("streaming") data but not control -("consistent") data. +("coherent") data. Setup shared control data ------------------------- -Once the DMA masks are set, the driver can allocate "consistent" (a.k.a. shared) +Once the DMA masks are set, the driver can allocate "coherent" (a.k.a. shared) memory. See Documentation/core-api/dma-api.rst for a full description of the DMA APIs. This section is just a reminder that it needs to be done before enabling DMA on the device. @@ -334,7 +335,7 @@ causes the PCI support to program CPU vector data into the PCI device capability registers. Many architectures, chip-sets, or BIOSes do NOT support MSI or MSI-X and a call to pci_alloc_irq_vectors with just the PCI_IRQ_MSI and PCI_IRQ_MSIX flags will fail, so try to always -specify PCI_IRQ_LEGACY as well. +specify PCI_IRQ_INTX as well. Drivers that have different interrupt handlers for MSI/MSI-X and legacy INTx should chose the right one based on the msi_enabled @@ -366,7 +367,7 @@ steps need to be performed: - Disable the device from generating IRQs - Release the IRQ (free_irq()) - Stop all DMA activity - - Release DMA buffers (both streaming and consistent) + - Release DMA buffers (both streaming and coherent) - Unregister from other subsystems (e.g. scsi or netdev) - Disable device from responding to MMIO/IO Port addresses - Release MMIO/IO Port resource(s) @@ -419,7 +420,7 @@ Once DMA is stopped, clean up streaming DMA first. I.e. unmap data buffers and return buffers to "upstream" owners if there is one. -Then clean up "consistent" buffers which contain the control data. +Then clean up "coherent" buffers which contain the control data. See Documentation/core-api/dma-api.rst for details on unmapping interfaces. |