Sorry, pls ignore the mail, I send it again. >-----Original Message----- >From: Fugang Duan [mailto:b38611@xxxxxxxxxxxxx] >Sent: Thursday, August 14, 2014 4:23 PM >To: wsa@xxxxxxxxxxxxx >Cc: linux-i2c@xxxxxxxxxxxxxxx; u.kleine-koenig@xxxxxxxxxxxxxx; Duan >Fugang-B38611 >Subject: [PATCH] i2c: imx: double check IIF in case interrupt lost > >In i2c_imx_read(): >... >result = i2c_imx_trx_complete(i2c_imx); >if (result) > return result; >.. > >If the current byte read complete, "IIF" status is set, and pend up one >GIC interrupt. In irq handler, wake up the wait queue >in .i2c_imx_trx_complete(). > >But, for imx6q platform with high bus and cpu loading test cases, after >long time test, sometime i2c interrupt is lost, but "IIF" is set, >according to current logic code, i2c_imx_trx_complete() still return "- >ETIMEDOUT", and then i2c host don't read the rest of data, i2c driver stop >transmit, disable controller and clock. Thus, i2c device cannot wait clock >and always drive the SDA line. > >So, SDA is pulled down by i2c device, which needs 9 clocks to recovery the >SDA line. > >To avoid the issue, we can double check IIF bit after timeout for waiting >event in .i2c_imx_trx_complete(), if IIF bit is set, process it in normal >flow. The patch just to double check IIF in case interrupt lost. > >Signed-off-by: Fugang Duan <B38611@xxxxxxxxxxxxx> >--- > drivers/i2c/busses/i2c-imx.c | 10 ++++++++-- > 1 files changed, 8 insertions(+), 2 deletions(-) > >diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c >index aa8bc14..f3845cb 100644 >--- a/drivers/i2c/busses/i2c-imx.c >+++ b/drivers/i2c/busses/i2c-imx.c >@@ -285,11 +285,17 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct >*i2c_imx, int for_busy) > > static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx) { >+ unsigned int temp; >+ > wait_event_timeout(i2c_imx->queue, i2c_imx->i2csr & I2SR_IIF, HZ / >10); > > if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) { >- dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__); >- return -ETIMEDOUT; >+ /* Double check IIF to avoid interrupt lost */ >+ temp = readb(i2c_imx->base + IMX_I2C_I2SR); >+ if (!(temp & I2SR_IIF)) { >+ dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", >__func__); >+ return -ETIMEDOUT; >+ } > } > dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__); > i2c_imx->i2csr = 0; >-- >1.7.8 -- 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
