https://github.com/torvalds/linux
Revision f1c089e3192f1afdfa76226dc38ef81b08ac810d authored by Mika Westerberg on 11 June 2011, 08:39:58 UTC, committed by David S. Miller on 11 June 2011, 23:25:16 UTC
Russell King said: > > So, to summarize what its doing: > > 1. It allocates buffers for rx and tx. > 2. It maps them with dma_map_single(). > This transfers ownership of the buffer to the DMA device. > 3. In ep93xx_xmit, > 3a. It copies the data into the buffer with skb_copy_and_csum_dev() > This violates the DMA buffer ownership rules - the CPU should > not be writing to this buffer while it is (in principle) owned > by the DMA device. > 3b. It then calls dma_sync_single_for_cpu() for the buffer. > This transfers ownership of the buffer to the CPU, which surely > is the wrong direction. > 4. In ep93xx_rx, > 4a. It calls dma_sync_single_for_cpu() for the buffer. > This at least transfers the DMA buffer ownership to the CPU > before the CPU reads the buffer > 4b. It then uses skb_copy_to_linear_data() to copy the data out. > At no point does it transfer ownership back to the DMA device. > 5. When the driver is removed, it dma_unmap_single()'s the buffer. > This transfers ownership of the buffer to the CPU. > 6. It frees the buffer. > > While it may work on ep93xx, it's not respecting the DMA API rules, > and with DMA debugging enabled it will probably encounter quite a few > warnings. This patch fixes these violations. Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com> Tested-by: Petr Stetiar <ynezz@true.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 1f758a4
Tip revision: f1c089e3192f1afdfa76226dc38ef81b08ac810d authored by Mika Westerberg on 11 June 2011, 08:39:58 UTC
net: ep93xx_eth: fix DMA API violations
net: ep93xx_eth: fix DMA API violations
Tip revision: f1c089e
File | Mode | Size |
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arch | ||
block | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.gitignore | -rw-r--r-- | 966 bytes |
.mailmap | -rw-r--r-- | 4.2 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 91.9 KB |
Kbuild | -rw-r--r-- | 2.4 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 189.8 KB |
Makefile | -rw-r--r-- | 52.6 KB |
README | -rw-r--r-- | 17.1 KB |
REPORTING-BUGS | -rw-r--r-- | 3.3 KB |
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