From: Michael Hennerich <[email protected]> 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.
Signed-off-by: Michael Hennerich <[email protected]> Signed-off-by: Mike Frysinger <[email protected]> --- 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. */ -- 1.7.4.rc1 -- 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
