On 08/12/2016 13:03, Geert Uytterhoeven wrote: > Måns Rullgård wrote: > >> Geert Uytterhoeven writes: >> >>> Can you fall back to PIO if requesting a channel fails? >> >> Why are we debating this nonsense? There is an easy fix that doesn't >> require changing the semantics of existing functions or falling back to >> slow pio. > > You still want to fall back to PIO if the DMA engine is not available > at all (e.g. DMA engine driver not compiled in, or module not loaded).
FWIW, the ECC engine is tied to the DMA engine. So PIO means not only taking a hit from tying up the CPU for a slooow transfer, but also a huge hit if ECC must be computed in SW. (A 100x perf degradation is not unlikely.) Regards.
