On Wed, 7 Mar 2012 20:41:03 +0800, Daniel Kurtz <djkurtz at chromium.org> wrote: > On Wed, Mar 7, 2012 at 8:12 PM, Chris Wilson <chris at chris-wilson.co.uk> > wrote: > > On Wed, ??7 Mar 2012 19:50:47 +0800, Daniel Kurtz <djkurtz at chromium.org> > > wrote: > >> Return -ENXIO if a device NAKs a transaction. > >> > >> Note: We should return -ETIMEDOUT, too if the transaction times out, > >> however, that error path is currently handled by the 'bit-bang fallback'. > >> > >> Signed-off-by: Daniel Kurtz <djkurtz at chromium.org> > > > > Can you clarify what the rule is if an error is detected part-way > > through a xfer? > > A priceless comment from drivers/i2c/i2c-core::i2c_transfer...
Thanks, that is about as consistent as one expects with i2c. ;) > This doesn't specify what to do if the transfer doesn't get an ACK > during another phase of the transfer. > However, it does say to send -ENXIO "if no ACK during address phase", > which is a subset of the possible no-ACK conditions during a transfer. > Thus, I choose to return ENXIO in all no-ACK cases, to ensure we send > it during the one case that is specified. This (and a summary of the rest) deserves to be captured as a comment in the code. -Chris -- Chris Wilson, Intel Open Source Technology Centre
