Hi, On Wed, Sep 22, 2010 at 05:39:16, Ben Dooks wrote: > On Tue, Sep 21, 2010 at 12:17:58PM -0700, Troy Kisky wrote: > > On 9/21/2010 4:24 AM, Sudhakar Rajashekhara wrote: > > > Hi, > > > > > > On Tue, Sep 21, 2010 at 09:43:28, Jon Povey wrote: > > >> When setting up to transmit, a race exists between the ISR and > > >> i2c_davinci_xfer_msg() trying to load the first byte and adjust counters. > > >> This is mostly visible for transmits > 1 byte long. > > >> > > >> The hardware starts sending immediately that MDR.STT is set. IMR trickery > > >> doesn't work because if we start sending, finish the first byte and an > > >> XRDY event occurs before we load IMR to unmask it, we never get an > > >> interrupt, and we timeout. > > >> > > >> Sudhakar Rajashekhara explains that at least OMAP-L138 requires MDR mode > > >> settings before DXR for correct behaviour, so load MDR first with > > >> STT cleared and later load again with STT set. > > >> > > >> Tested on DM355 connected to Techwell TW2836 and Wolfson WM8985 > > >> > > >> Signed-off-by: Jon Povey <jon.po...@racelogic.co.uk> > > >> CC: Sudhakar Rajashekhara <sudhakar....@ti.com> > > >> CC: Troy Kisky <troy.ki...@boundarydevices.com> > > >> --- > > >> Reworked after comments by Troy and Sudhakar. > > >> > > >> Looking at the datasheet it seemed like setting STP without STT early > > >> might cause a stray STOP to be generated, so I moved it into the second > > >> MDR load. > > >> > > >> This passes a quick smoke test but I can't do much more testing right at > > >> the moment. Sudhakar, your comments would be welcomed. > > >> > > > > > > Looks good to me. I can test on couple of platforms I have and update the > > > result > > > by tomorrow. > > > > > > Thanks, > > > Sudhakar > > > > > > > > > > > I like it too. I hope it works for omap. > > > > Thanks as well > > Troy > > Ok, any objections to this being applied, or should I wait? >
I am stuck in some other work. If you can wait till I test it, that'll be good. Thanks, Sudhakar _______________________________________________ Davinci-linux-open-source mailing list Davinci-linux-open-source@linux.davincidsp.com http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
