diff options
Diffstat (limited to 'Documentation/debugging-via-ohci1394.txt')
| -rw-r--r-- | Documentation/debugging-via-ohci1394.txt | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/Documentation/debugging-via-ohci1394.txt b/Documentation/debugging-via-ohci1394.txt index de4804e8b396..c360d4e91b48 100644 --- a/Documentation/debugging-via-ohci1394.txt +++ b/Documentation/debugging-via-ohci1394.txt @@ -36,14 +36,15 @@ available (notebooks) or too slow for extensive debug information (like ACPI). Drivers ------- -The OHCI-1394 drivers in drivers/firewire and drivers/ieee1394 initialize -the OHCI-1394 controllers to a working state and can be used to enable -physical DMA. By default you only have to load the driver, and physical -DMA access will be granted to all remote nodes, but it can be turned off -when using the ohci1394 driver. - -Because these drivers depend on the PCI enumeration to be completed, an -initialization routine which can runs pretty early (long before console_init(), +The ohci1394 driver in drivers/ieee1394 initializes the OHCI-1394 controllers +to a working state and enables physical DMA by default for all remote nodes. +This can be turned off by ohci1394's module parameter phys_dma=0. + +The alternative firewire-ohci driver in drivers/firewire uses filtered physical +DMA, hence is not yet suitable for remote debugging. + +Because ohci1394 depends on the PCI enumeration to be completed, an +initialization routine which runs pretty early (long before console_init() which makes the printk buffer appear on the console can be called) was written. To activate it, enable CONFIG_PROVIDE_OHCI1394_DMA_INIT (Kernel hacking menu: |