On Mon, Apr 09, 2018 at 02:59:57PM +0300, Sergey Suloev wrote: > > > But as soon as sun4i SPI driver is correctly declaring > > > max_transfer_size then "smart" clients will work well by limiting a > > > single transfer size to FIFO depth. I tested it with real hardware, > > > again. > > This is really not my point. What would prevent you from doing > > multiple transfers in that case, and filling the FIFO entirely, > > waiting for it to be done, then resuming until you have sent the right > > number of bytes? > > Because it makes no sense IMHO. I can't see any single point in allowing > long PIO transfers. Can you find at least one ?
I'm probably going to state the obvious here, but to allow long transfers? > I think we should reuse as much SPI core code as possible. The SPI > core can handle an SPI message with multiple transfers, all we need > is to have max_transfer_size = FIFO depth and restrict it in > transfer_one(). There's not a single call to the max_transfer_size hook in the SPI core in 4.16, so that seems a bit too optimistic. Maxime -- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
Description: PGP signature