On Thu, Nov 19, 2015 at 05:15:38PM +0000, Mark Brown wrote: > On Thu, Nov 19, 2015 at 04:00:45PM +0100, Martin Sperl wrote: > > On the bcm2835 there are also some “limitations” (when transfers are not > > aligned > > to word, transfers>65535 can’t DMA) which we work around right now > > inefficiently. > > Alignment is a general issue which all clients should be trying to > ensure as a matter of course - never mind individual blocks of hardware, > some common CPU architectures suffer noticable penalties from unaligned > accesses so it's just generally good practice to try to avoid them. > > You shouldn't be doing anything about transfer size limitations in your > driver, if you have this restriction you should be adding code to the > core and just flagging the limit in your driver.
So for transfer size limitations, are you speaking of the same thing as Heiner (who began this post mentioning *message* size limitations)? I read a difference between the two, where a transfer size limitation might mean that one could improve the SPI core to just split transfers up into multiple sub-transfers, and still complete the whole spi_message (and therefore the protocol driver has less to worry about). But if we're talking about spi_message limitations, then this would be more exposed to the protocol driver. Or maybe I'm just reading this all wrong and am confused. Please enlighten. Regards, Brian -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
