> > If the driver could not handle zero length transfer, then the driver > > should reject it (just like unsupported transfer mode). Then the > > behavior will be 'assert chip select and wait some time' or 'rejected > > by the driver'. > > This would be OK. It would not be hard to fix pxa2xx_spi, for example, > to reject zero-length transfers in DMA mode, as long as it is acceptable > to reject the message in mid-message.
Such "illegal message" rejection is best done early; "fail-fast". Mid-message rejection isn't wrong, but it's a rude policy. It'd be best to fix pxa2xx_spi to not start zero-length DMAs. > If it were necessary to scan a > whole message for zero-length transfers and refuse to queue an offending > message, then that adds burden to all messages. Sanity checking messages as they're submitted is easy; and it's also the natural point for setting up DMA mappings (and making those cachelines available for better use). - Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
