• Dan Williams's avatar
    async_tx: kill tx_set_src and tx_set_dest methods · 0036731c
    Dan Williams authored
    The tx_set_src and tx_set_dest methods were originally implemented to allow
    an array of addresses to be passed down from async_xor to the dmaengine
    driver while minimizing stack overhead.  Removing these methods allows
    drivers to have all transaction parameters available at 'prep' time, saves
    two function pointers in struct dma_async_tx_descriptor, and reduces the
    number of indirect branches..
    
    A consequence of moving this data to the 'prep' routine is that
    multi-source routines like async_xor need temporary storage to convert an
    array of linear addresses into an array of dma addresses.  In order to keep
    the same stack footprint of the previous implementation the input array is
    reused as storage for the dma addresses.  This requires that
    sizeof(dma_addr_t) be less than or equal to sizeof(void *).  As a
    consequence CONFIG_DMADEVICES now depends on !CONFIG_HIGHMEM64G.  It also
    requires that drivers be able to make descriptor resources available when
    the 'prep' routine is polled.
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    Acked-by: default avatarShannon Nelson <shannon.nelson@intel.com>
    0036731c
ioat_dma.c 37.3 KB