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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-05-30 12:06:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-05-30 12:06:15 -0700 |
| commit | 1326af2464fc29290d1710447297d33a90a6ece4 (patch) | |
| tree | d052eeff789e56a83dd881ef6efa809f73e28b43 /Documentation | |
| parent | 24e19d279f9e289e965b4bc4710fbccab824c4c4 (diff) | |
| parent | 2fe2023adf695d08af5b598b2be3b288a95d563c (diff) | |
Merge tag 'firewire-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394
Pull firewire fix from Stefan Richter:
"A regression fix for the IEEE 1394 subsystem: re-enable IRQ-based
asynchronous request reception at addresses below 128 TB"
* tag 'firewire-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
firewire: revert to 4 GB RDMA, fix protocols using Memory Space
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/debugging-via-ohci1394.txt | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/Documentation/debugging-via-ohci1394.txt b/Documentation/debugging-via-ohci1394.txt index fa0151a712f..5c9a567b3fa 100644 --- a/Documentation/debugging-via-ohci1394.txt +++ b/Documentation/debugging-via-ohci1394.txt @@ -25,9 +25,11 @@ using data transfer rates in the order of 10MB/s or more. With most FireWire controllers, memory access is limited to the low 4 GB of physical address space. This can be a problem on IA64 machines where memory is located mostly above that limit, but it is rarely a problem on -more common hardware such as x86, x86-64 and PowerPC. However, at least -Agere/LSI FW643e and FW643e2 controllers are known to support access to -physical addresses above 4 GB. +more common hardware such as x86, x86-64 and PowerPC. + +At least LSI FW643e and FW643e2 controllers are known to support access to +physical addresses above 4 GB, but this feature is currently not enabled by +Linux. Together with a early initialization of the OHCI-1394 controller for debugging, this facility proved most useful for examining long debugs logs in the printk @@ -101,8 +103,9 @@ Step-by-step instructions for using firescope with early OHCI initialization: compliant, they are based on TI PCILynx chips and require drivers for Win- dows operating systems. - The mentioned kernel log message contains ">4 GB phys DMA" in case of - OHCI-1394 controllers which support accesses above this limit. + The mentioned kernel log message contains the string "physUB" if the + controller implements a writable Physical Upper Bound register. This is + required for physical DMA above 4 GB (but not utilized by Linux yet). 2) Establish a working FireWire cable connection: |