Ben,
Jon Povey <jon.po...@racelogic.co.uk> writes:
> 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.
>
> Tested on DM355 connected to Techwell TW2836 and Wolfson WM8985
>
> Signed-off-by: Jon Povey <jon.po...@racelogic.co.uk>
> Acked-by: Troy Kisky <troy.ki...@boundarydevices.com>
> Tested-by: Sudhakar Rajashekhara <sudhakar....@ti.com>
> Acked-by: Kevin Hilman <khil...@deeprootsystems.com>
> ---
> 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.
can you get this one into 2.6.36 please?
Thanks,
Kevin
>
> 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,
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