Hello Jeff, On Mon, Sep 01, 2014 at 09:30:31AM -0500, Jeff Epler wrote: > Unfortunately, I found that there were frequent large latencies, some > over 10ms, when using /dev/spidev. This seems to be typical of others' > experience using it (for instance, one can find threads discussing > disappointing RT performance of SPI on the beaglebone and pandaboard; at > least one raspberry pi project chose to implement a pure userspace SPI > driver instead of using spidev) > > At all levels of the SPI stack, I found things that could be improved if > lowest delays are the goal. I doubt that in their current form these > changes are suitable to be incorporated in preempt-rt, but I hope that > this might spur some discussion that would ultimately lead to better > realtime performance of SPI in the preempt-rt kernel. I wonder why you didn't consider mainline as target for your patches instead of preempt-rt. Also you might want to cc the spi maintainer on this topic. I didn't check in detail what you did, but if it's useful for others it would be a pity if it were not picked up because the responsible people were not aware of your effort. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
