• Juha Yrjölä's avatar
    [PATCH] ARM: OMAP: DMA updates to OMAP MMC driver · 15dc0cde
    Juha Yrjölä authored
    DMA updates to the OMAP MMC driver (Juha):
    
    	* Accept multi-segment scatterlist requests to reduce the cost
    	  of data transfer operations, increasing speed dramatically
    	* Release DMA channel lazily for a minor performance boost
    	* Synchronize the completion of a request to both DMA transfer
    	  completion and command completion to work around a problem of
    	  some response IRQs being lost
    
    Also, updates from DB for handling the individual DMA segments:
    
    	* Use the correct sg_dma_*() calls;
    	* Return to the previous scheme of doing DMA in frames of up
    	  no more than one FIFO's worth of data, and
    	* Don't print messages in the curious "DMA IRQ with DMA still
    	  pending" case.
    
    This provides about a 10% improvement in elapsed time during large DMA
    transfers, 100% improvement in kernel time, and orders of magnitude
    reduction in IRQ count.
    Signed-off-by: default avatarJuha Yrjölä <juha.yrjola@nokia.com>
    Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
    15dc0cde
omap.c 32.4 KB