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authorClemens Ladisch <clemens@ladisch.de>2010-11-26 08:57:31 +0100
committerStefan Richter <stefanr@s5r6.in-berlin.de>2010-12-13 20:39:13 +0100
commit7a39d8b82165462729d09066bddb395a19025acd (patch)
treec0fea8d963b7f421e97dccacb059cfca610072de /drivers/firewire/Kconfig
parent5878730be4e3d0c9527d6f2f688874e38acacc98 (diff)
downloadlinaro-lsk-7a39d8b82165462729d09066bddb395a19025acd.tar.gz
firewire: ohci: Asynchronous Reception rewrite
Move the AR DMA descriptors out of the buffer pages, and map the buffer pages linearly into the kernel's address space. This allows the driver to ignore any page boundaries in the DMA data and thus to avoid any copying around of packet payloads. This fixes the bug where S800 packets that are so big (> 4080 bytes) that they can be split over three pages were not handled correctly. Due to the changed algorithm, we can now use arbitrarily many buffer pages, which improves performance because the controller can more easily unload its DMA FIFO. Furthermore, using streaming DMA mappings should improve perfomance on architectures where coherent DMA mappings are not cacheable. Even on other architectures, the caching behaviour should be improved slightly because the CPU no longer writes to the buffer pages. v2: Detect the last filled buffer page by searching the descriptor's residual count value fields in order (like in the old code), instead of going backwards through the transfer status fields; it looks as if some controllers do not set the latter correctly. v3: Fix an old resume bug that would now make the handler run into a BUG_ON, and replace that check with more useful error handling. Increase the buffer size for better performance with non-TI chips. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Maxim Levitsky writes: Works almost perfectly. I can still see RCODE_BUSY errors sometimes, not very often though. 64K here eliminates these errors completely. This is most likely due to nouveau drivers and lowest perf level I use to lower card temperature. That increases latencies too much I think. Besides that the IO is just perfect. Tested-by: Maxim Levitsky <maximlevitsky@gmail.com> Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire/Kconfig')
-rw-r--r--drivers/firewire/Kconfig2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/firewire/Kconfig b/drivers/firewire/Kconfig
index 40a222e19b2..68f942cb30f 100644
--- a/drivers/firewire/Kconfig
+++ b/drivers/firewire/Kconfig
@@ -19,7 +19,7 @@ config FIREWIRE
config FIREWIRE_OHCI
tristate "OHCI-1394 controllers"
- depends on PCI && FIREWIRE
+ depends on PCI && FIREWIRE && MMU
help
Enable this driver if you have a FireWire controller based
on the OHCI specification. For all practical purposes, this