On Wed, Jul 20, 2016 at 02:03:03PM -0500, Rob Herring wrote: > On Tue, Jul 19, 2016 at 08:41:24PM -0700, Andrey Pronin wrote: Hi Rob, > As I mentioned, there may be common properties. It doesn't seem you > looked, so I did: > > - spi-rx-delay-us - (optional) Microsecond delay after a read transfer. > - spi-tx-delay-us - (optional) Microsecond delay after a write transfer. > > Seems to me setting one or both of these should work for you. > Yes, good catch, my fault I didn't see those. But they are not exactly what I mean and need. I don't need delay after each read or write transfer. What is needed is a guaranteed time between transfers. So, if the next transaction doesn't come withing the next X ms (or us), we don't waste time on inserting a delays after this transaction at all. Following the description and always inserting a delay must work well for short microseconds-long delays. For longer milliseconds-long delays a different strategy of checking the time when the previous transaction was and only delaying if it was not too long ago is better. Thus, I won't be able to re-use these properties anyways based on their current description in bindings/spi/spi-bus.txt. > > +- sleep-delay-ms: Time after the last SPI activity, after which the chip > > + may go to sleep. > > +- wake-start-delay-ms: Time after initiating wake up before the chip is > > + ready to accept commands over SPI. > > I also asked why these 2 can't be hard-coded in the driver? > Sorry, I just updated this patch description in v2 to indicate why they are not hard-coded, but didn't answer explicitly. As the firmware changes, a different revision of it can have a different time before it sleeps in its configuration, or the time it takes it to startup may be different. Thus, there's a way to set it here w/o changing the driver. Andrey -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
