| Message ID | 1416518925-20679-4-git-send-email-al.kochet@gmail.com |
|---|---|
| State | Superseded |
| Delegated to: | Wolfram Sang |
| Headers | show |
On Fri, Nov 21, 2014 at 01:28:44AM +0400, Alexander Kochetkov wrote: > Arbitration Lost is a expected situation in a multimaster environment. > IP correctly detect it. > > The only reason for reseting IP in the AL case is to be sure to > avoid advisory 1.94 (omap3) and errata i595 (omap4): > "I2C: After an Arbitration is Lost the Module Incorrectly Starts > the Next Transfer" with workaround: "The MST and STT bits inside > I2C_CON should be set to 1 at the same moment (avoid setting the > MST bit to 1 while STT = 0)." > > The driver never writes MST and STT bits separately and doesn't > create condition for errata. So the reset is not necessary. > > Tested on Beagleboard XM C. > > Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com> Tested on BBB and AM437x Starter Kit Tested-by: Felipe Balbi <balbi@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> > --- > drivers/i2c/busses/i2c-omap.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index 3ffb9c0..47103e7 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -707,13 +707,17 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap, > return 0; > > /* We have an error */ > - if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR | > + if (dev->cmd_err & (OMAP_I2C_STAT_ROVR | > OMAP_I2C_STAT_XUDF)) { > omap_i2c_reset(dev); > __omap_i2c_init(dev); > return -EIO; > } > > + if (dev->cmd_err & OMAP_I2C_STAT_AL) { > + return -EIO; > + } > + > if (dev->cmd_err & OMAP_I2C_STAT_NACK) { > if (msg->flags & I2C_M_IGNORE_NAK) > return 0; > -- > 1.7.9.5 >
On Fri, Nov 21, 2014 at 01:28:44AM +0400, Alexander Kochetkov wrote: > Arbitration Lost is a expected situation in a multimaster environment. > IP correctly detect it. > > The only reason for reseting IP in the AL case is to be sure to > avoid advisory 1.94 (omap3) and errata i595 (omap4): > "I2C: After an Arbitration is Lost the Module Incorrectly Starts > the Next Transfer" with workaround: "The MST and STT bits inside > I2C_CON should be set to 1 at the same moment (avoid setting the > MST bit to 1 while STT = 0)." > > The driver never writes MST and STT bits separately and doesn't > create condition for errata. So the reset is not necessary. > > Tested on Beagleboard XM C. > > Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com> > --- > drivers/i2c/busses/i2c-omap.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index 3ffb9c0..47103e7 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -707,13 +707,17 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap, > return 0; > > /* We have an error */ > - if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR | > + if (dev->cmd_err & (OMAP_I2C_STAT_ROVR | > OMAP_I2C_STAT_XUDF)) { > omap_i2c_reset(dev); > __omap_i2c_init(dev); > return -EIO; > } > > + if (dev->cmd_err & OMAP_I2C_STAT_AL) { > + return -EIO; > + } The errno for AL is -EAGAIN. Curly braces are not needed. > + > if (dev->cmd_err & OMAP_I2C_STAT_NACK) { > if (msg->flags & I2C_M_IGNORE_NAK) > return 0; > -- > 1.7.9.5 >
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index 3ffb9c0..47103e7 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -707,13 +707,17 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap, return 0; /* We have an error */ - if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR | + if (dev->cmd_err & (OMAP_I2C_STAT_ROVR | OMAP_I2C_STAT_XUDF)) { omap_i2c_reset(dev); __omap_i2c_init(dev); return -EIO; } + if (dev->cmd_err & OMAP_I2C_STAT_AL) { + return -EIO; + } + if (dev->cmd_err & OMAP_I2C_STAT_NACK) { if (msg->flags & I2C_M_IGNORE_NAK) return 0;
Arbitration Lost is a expected situation in a multimaster environment. IP correctly detect it. The only reason for reseting IP in the AL case is to be sure to avoid advisory 1.94 (omap3) and errata i595 (omap4): "I2C: After an Arbitration is Lost the Module Incorrectly Starts the Next Transfer" with workaround: "The MST and STT bits inside I2C_CON should be set to 1 at the same moment (avoid setting the MST bit to 1 while STT = 0)." The driver never writes MST and STT bits separately and doesn't create condition for errata. So the reset is not necessary. Tested on Beagleboard XM C. Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com> --- drivers/i2c/busses/i2c-omap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)