> > Bus clear feature of Tegra I2C controller helps to recover from bus > > hang when I2C master loses the bus arbitration due to the slave device > > holding SDA LOW continuously for some unknown reasons. > > > > Per I2C specification, the device that held the bus LOW should release > > it within 9 clock pulses. > > > > During bus clear operation, Tegra I2C controller sends 9 clock pulses > > and terminates the transaction with STOP condition. > > Upon successful bus clear operation, bus goes to idle state and driver > > retries the transaction. > > > > Acked-by: Thierry Reding <[email protected]> > > Reviewed-by: Dmitry Osipenko <[email protected]> > > Signed-off-by: Sowjanya Komatineni <[email protected]> > > We have a bus recovery infrastructure in the core. Tying your code into it > should be easy. You probably just need a 'struct i2c_bus_recovery_info', > populate the 'recover_bus' callback with 'tegra_i2c_issue_bus_clear()', and > attach this struct to the 'struct adapter' if the IP core supports bus > recovery, otherwise leave it empty. > Then, you can... > > > +static int tegra_i2c_issue_bus_clear(struct tegra_i2c_dev *i2c_dev) { > > + int err; > > + unsigned long time_left; > > + u32 reg; > > + > > + if (i2c_dev->hw->supports_bus_clear) { > >... remove the if here because the core will check for a valid >i2c_bus_recovery_info... > > > @@ -759,6 +818,13 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev > > *i2c_dev, > > return 0; > > > > tegra_i2c_init(i2c_dev); > > + /* start recovery upon arbitration loss in single master mode */ > > + if (i2c_dev->msg_err == I2C_ERR_ARBITRATION_LOST) { > > + if (!i2c_dev->is_multimaster_mode) > > + return tegra_i2c_issue_bus_clear(i2c_dev); > >... and use simply i2c_recover_bus() here. > > This will help making bus recovery use consistent across drivers. > > OK, Will update to use i2c_bus_recovery_info
Sowjanya
