From de919ff6a0060510b099405d9b8f9413aba9ae14 Mon Sep 17 00:00:00 2001 From: Dmitry Bazhenov Date: Wed, 21 Sep 2016 08:51:03 +0200 Subject: [PATCH] i2c: octeon: Avoid sending STOP during recovery Due to a bug in the ThunderX I2C hardware sending STOP during a recovery attempt could lock up the hardware. To work around this problem do not send STOP at the beginning of the recovery but use the override registers to bring the TWSI including the high-level controller out of the bad state. Signed-off-by: Dmitry Bazhenov Signed-off-by: Jan Glauber [Changed commit message] Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-octeon-core.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c index f322242cdbf8..7d4df8383b38 100644 --- a/drivers/i2c/busses/i2c-octeon-core.c +++ b/drivers/i2c/busses/i2c-octeon-core.c @@ -783,13 +783,14 @@ static void octeon_i2c_prepare_recovery(struct i2c_adapter *adap) { struct octeon_i2c *i2c = i2c_get_adapdata(adap); + octeon_i2c_hlc_disable(i2c); + /* - * The stop resets the state machine, does not _transmit_ STOP unless - * engine was active. + * Bring control register to a good state regardless + * of HLC state. */ - octeon_i2c_stop(i2c); + octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB); - octeon_i2c_hlc_disable(i2c); octeon_i2c_write_int(i2c, 0); } @@ -797,6 +798,15 @@ static void octeon_i2c_unprepare_recovery(struct i2c_adapter *adap) { struct octeon_i2c *i2c = i2c_get_adapdata(adap); + /* + * Generate STOP to finish the unfinished transaction. + * Can't generate STOP via the TWSI CTL register + * since it could bring the TWSI controller into an inoperable state. + */ + octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR | TWSI_INT_SCL_OVR); + udelay(5); + octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR); + udelay(5); octeon_i2c_write_int(i2c, 0); } -- 2.20.1