On Wed, Aug 08, 2018 at 10:26:42AM +0800, Baolin Wang wrote: > Sorry for confusing. Let me try to explain it explicitly. > We can set the word size (bits_per_word) for each transmission, for > our SPI controller, after every word size transmission, we need one > interval time (hardware automatically) to make sure the slave has > enough time to receive the whole data. OK, so it's an inter word delay. Some other controllers definitely have the same feature. > Yes, I agree we should configure it at runtime by the device, but we > did not find one member to use in 'struct spi_transfer', we just find > one similar 'delay_usecs' member in 'struct spi_transfer' but not > same. We can use 'delay_usecs' to set our hardware interval value, > but we should clean it when transfer is done, since we do not need to > delay after the transfer in spi_transfer_one _message(). Or can we add > one new member maybe named 'word_interval' to indicate the interval > time between word size transmission? Right, I don't think we added this yet (if we did I can't see it). I'd add a new field to spi_transfer for this, then other controllers with the same support can implement it as well and drivers can start using it too.
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