[PARPORT] ECP DMA slower than rep insb ?

Pascal Brisset (Pascal.Brisset@wanadoo.fr)
Mon, 24 Aug 1998 10:56:01 +0200 (MET DST)


Does anyone here have experience with fast ECP devices ? I am trying
to interface with a parallel-port camera which support ECP (Nec PCAM).
DMA from the ECP to memory yields 440 kB/s, but I can get as much as
670 kB/s without DMA (trivial "rep insb" reads). Even worse, transfers
with the Windows driver seem to be roughly 30% faster (need to confirm
this). Have I missed something in the DMA/ECP specs or in parport_pc.c
which could explain these figures ? I'm using 2.0.34 with real-time
patches (rt-linux) on a P166+ASUS board.

-- Pascal Brisset <Pascal.Brisset@wanadoo.fr>

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This archive was generated by hypermail 2.0b3 on Wed 30 Dec 1998 - 10:18:07 EST