On Fri, Sep 24, 2010 at 07:37:03AM -0700, Kevin Hilman wrote: > "Sudhakar Rajashekhara" <sudhakar.raj@xxxxxx> writes: > > > 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.povey@xxxxxxxxxxxxxxx> > >> CC: Sudhakar Rajashekhara <sudhakar.raj@xxxxxx> > >> CC: Troy Kisky <troy.kisky@xxxxxxxxxxxxxxxxxxx> > >> --- > > > > Tested-by: Sudhakar Rajashekhara <sudhakar.raj@xxxxxx> > > > > Tested with audio loopback on OMAP-L138, OMAP-L137 and DM365. Also tested with > > i2cdetect function which probes all the devices on the i2c bus. > > > Ben, can you queue this one for 2.6.37 with the addition of: If it is a worthwhile bugfix i'll send it for the next -rc. > Acked-by: Troy Kisky <troy.kisky@xxxxxxxxxxxxxxxxxxx> > Tested-by: Sudhakar Rajashekhara <sudhakar.raj@xxxxxx> > Acked-by: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> > > Thanks, > > Kevin > -- -- Ben Q: What's a light-year? A: One-third less calories than a regular year. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
