138f4c359d
Channel switching is problematic for some dmaengine drivers as the architecture precludes separating the ->prep from ->submit. In these cases the driver can select ASYNC_TX_DISABLE_CHANNEL_SWITCH to modify the async_tx allocator to only return channels that support all of the required asynchronous operations. For example MD_RAID456=y selects support for asynchronous xor, xor validate, pq, pq validate, and memcpy. When ASYNC_TX_DISABLE_CHANNEL_SWITCH=y any channel with all these capabilities is marked DMA_ASYNC_TX allowing async_tx_find_channel() to quickly locate compatible channels with the guarantee that dependency chains will remain on one channel. When ASYNC_TX_DISABLE_CHANNEL_SWITCH=n async_tx_find_channel() may select channels that lead to operation chains that need to cross channel boundaries using the async_tx channel switch capability. Signed-off-by: Dan Williams <dan.j.williams@intel.com> |
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| .. | ||
| ioat | ||
| ipu | ||
| dmaengine.c | ||
| dmatest.c | ||
| dw_dmac_regs.h | ||
| dw_dmac.c | ||
| fsldma.c | ||
| fsldma.h | ||
| iop-adma.c | ||
| iovlock.c | ||
| Kconfig | ||
| Makefile | ||
| mv_xor.c | ||
| mv_xor.h | ||