On Sun, May 09, 2010 at 07:04:47AM -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 8 extra
> clocks until the SDA is properly released.
>
> Signed-off-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
> Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>
> ---
> Note: this requires the existing Blackfin TWI patches already sent out
hmm, it is late in the -rc series for anything other than critical
bugfixes, will update series tomorrow.
> 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..f9c05e1 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 salve devices, may drive SDA low after a transfer
spello: slave
> + * finishes. To release the bus this code generates up to 8
> + * extra clocks until SDA is released.
> + */
> +
> + if (read_MASTER_STAT(iface) & SDASEN) {
> + int cnt = 8;
> + 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
>
--
--
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 majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
