From 7a39d8b82165462729d09066bddb395a19025acd Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Fri, 26 Nov 2010 08:57:31 +0100 Subject: 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 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 Signed-off-by: Stefan Richter --- drivers/firewire/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/firewire/Kconfig') diff --git a/drivers/firewire/Kconfig b/drivers/firewire/Kconfig index 40a222e19b2d..68f942cb30f2 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 -- cgit v1.2.3