On Tue, Oct 12, 2010 at 01:47:05PM +0900, Jon Povey wrote: > This patch is an improvement to 4bba0fd8d1c6d405df666e2573e1a1f917098be0 > which got to mainline a little early. > > 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.
ok, will look at sending this with tomorrow. > Tested on DM355 connected to Techwell TW2836 and Wolfson WM8985 > > Signed-off-by: Jon Povey <[email protected]> > Acked-by: Troy Kisky <[email protected]> > Tested-by: Sudhakar Rajashekhara <[email protected]> > Acked-by: Kevin Hilman <[email protected]> > --- > This patches to what was v4 of the original patch. > > The original patch which made it to 2.6.36-rc7 will as I understand it have > introduced a regression for OMAP-L138 so this patch is a regression fix and > wants to get into 2.6.36. > > drivers/i2c/busses/i2c-davinci.c | 24 +++++++++++++++--------- > 1 files changed, 15 insertions(+), 9 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-davinci.c > b/drivers/i2c/busses/i2c-davinci.c > index b8feac5..5795c83 100644 > --- a/drivers/i2c/busses/i2c-davinci.c > +++ b/drivers/i2c/busses/i2c-davinci.c > @@ -331,21 +331,16 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct > i2c_msg *msg, int stop) > INIT_COMPLETION(dev->cmd_complete); > dev->cmd_err = 0; > > - /* Take I2C out of reset, configure it as master and set the > - * start bit */ > - flag = DAVINCI_I2C_MDR_IRS | DAVINCI_I2C_MDR_MST | DAVINCI_I2C_MDR_STT; > + /* Take I2C out of reset and configure it as master */ > + flag = DAVINCI_I2C_MDR_IRS | DAVINCI_I2C_MDR_MST; > > /* if the slave address is ten bit address, enable XA bit */ > if (msg->flags & I2C_M_TEN) > flag |= DAVINCI_I2C_MDR_XA; > if (!(msg->flags & I2C_M_RD)) > flag |= DAVINCI_I2C_MDR_TRX; > - if (stop) > - flag |= DAVINCI_I2C_MDR_STP; > - if (msg->len == 0) { > + if (msg->len == 0) > flag |= DAVINCI_I2C_MDR_RM; > - flag &= ~DAVINCI_I2C_MDR_STP; > - } > > /* Enable receive or transmit interrupts */ > w = davinci_i2c_read_reg(dev, DAVINCI_I2C_IMR_REG); > @@ -358,17 +353,28 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct > i2c_msg *msg, int stop) > dev->terminate = 0; > > /* > + * Write mode register first as needed for correct behaviour > + * on OMAP-L138, but don't set STT yet to avoid a race with XRDY > + * occuring before we have loaded DXR > + */ > + davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); > + > + /* > * First byte should be set here, not after interrupt, > * because transmit-data-ready interrupt can come before > * NACK-interrupt during sending of previous message and > * ICDXR may have wrong data > + * It also saves us one interrupt, slightly faster > */ > if ((!(msg->flags & I2C_M_RD)) && dev->buf_len) { > davinci_i2c_write_reg(dev, DAVINCI_I2C_DXR_REG, *dev->buf++); > dev->buf_len--; > } > > - /* write the data into mode register; start transmitting */ > + /* Set STT to begin transmit now DXR is loaded */ > + flag |= DAVINCI_I2C_MDR_STT; > + if (stop && msg->len != 0) > + flag |= DAVINCI_I2C_MDR_STP; > davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); > > r = wait_for_completion_interruptible_timeout(&dev->cmd_complete, > -- > 1.6.3.3 > > -- > 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 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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
