On Mon, May 10, 2010 at 11:33:44AM -0400, Mike Frysinger wrote:
> From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
>
> 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 <michael.hennerich@xxxxxxxxxx>
> Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>
> ---
> 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 majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Ben (ben@xxxxxxxxx, 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 majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
