On Mon, May 10, 2010 at 11:33:44AM -0400, Mike Frysinger wrote: > From: Michael Hennerich <[email protected]> > > Faulty slave devices might drive SDA low after a transfer finishes. So, > when this scenario is detected, have the master generate up to 9 extra > clocks until the SDA is properly released.
This doesn't apply to my for-2635/i2c-bfin tree, can't find the BUFWERR patch. will check to see if theres's something i've missed.. > Signed-off-by: Michael Hennerich <[email protected]> > Signed-off-by: Mike Frysinger <[email protected]> > --- > v2 > - fix typo in comment pointed out by Ben > - use 9 clocks rather than 8 to cover a possible NACK pointed out by > Michael > > drivers/i2c/busses/i2c-bfin-twi.c | 22 ++++++++++++++++++++++ > 1 files changed, 22 insertions(+), 0 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-bfin-twi.c > b/drivers/i2c/busses/i2c-bfin-twi.c > index fb26e5c..1ee9d5a 100644 > --- a/drivers/i2c/busses/i2c-bfin-twi.c > +++ b/drivers/i2c/busses/i2c-bfin-twi.c > @@ -20,6 +20,7 @@ > #include <linux/completion.h> > #include <linux/interrupt.h> > #include <linux/platform_device.h> > +#include <linux/delay.h> > > #include <asm/blackfin.h> > #include <asm/portmux.h> > @@ -159,6 +160,27 @@ static void bfin_twi_handle_interrupt(struct > bfin_twi_iface *iface, > if (mast_stat & BUFWRERR) > dev_dbg(&iface->adap.dev, "Buffer Write Error\n"); > > + /* Faulty slave devices, may drive SDA low after a transfer > + * finishes. To release the bus this code generates up to 9 > + * extra clocks until SDA is released. > + */ > + > + if (read_MASTER_STAT(iface) & SDASEN) { > + int cnt = 9; > + do { > + write_MASTER_CTL(iface, SCLOVR); > + udelay(6); > + write_MASTER_CTL(iface, 0); > + udelay(6); > + } while ((read_MASTER_STAT(iface) & SDASEN) && cnt--); > + > + write_MASTER_CTL(iface, SDAOVR | SCLOVR); > + udelay(6); > + write_MASTER_CTL(iface, SDAOVR); > + udelay(6); > + write_MASTER_CTL(iface, 0); > + } > + > /* If it is a quick transfer, only address without data, > * not an err, return 1. > */ > -- > 1.7.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Ben ([email protected], http://www.fluff.org/) 'a smiley only costs 4 bytes' -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
