On 20-06-22, 22:13, Samuel Holland wrote: > The sun4i DMA engine supports transfer sizes up to 128k for normal DMA > and 16M for dedicated DMA, as documented in the A10 and A20 manuals. > > Since this is larger than the default segment size limit (64k), exposing > the real limit reduces the number of transfers needed for a transaction. > However, because the device can only report one segment size limit, we > have to expose the smaller limit from normal DMA. > > One complication is that the driver combines pairs of periodic transfers > to reduce programming overhead. This only works when the period size is > at most half of the maximum transfer size. With the default 64k segment > size limit, this was always the case, but for normal DMA it is no longer > guaranteed. Skip the optimization if the period is too long; even > without it, the overhead is less than before. Applied, thanks -- ~Vinod
