On Wed, Sep 11, 2024 at 04:39:45PM +0800, Kimriver Liu wrote:
> It was observed that issuing ABORT bit (IC_ENABLE[1]) will not
> work when IC_ENABLE is already disabled.
>
> Check if ENABLE bit (IC_ENABLE[0]) is disabled when the controller
> is holding SCL low. If ENABLE bit is disabled, the software need
> to enable it before trying to issue ABORT bit. otherwise,
> the controller ignores any write to ABORT bit.
>
> These kernel logs show up whenever an I2C transaction is
> attempted after this failure.
> i2c_designware e95e0000.i2c: timeout waiting for bus ready
> i2c_designware e95e0000.i2c: timeout in disabling adapter
>
> The patch can be fix the controller cannot be disabled while
> SCL is held low in ENABLE bit is already disabled.
...
> +/*
> + * This functions waits controller idling before disabling I2C
> + * When the controller is not in the IDLE state,
> + * MST_ACTIVITY bit (IC_STATUS[5]) is set.
> + * Values:
> + * 0x1 (ACTIVE): Controller not idle
> + * 0x0 (IDLE): Controller is idle
> + * The function is called after returning the end of the current transfer
> + * Returns:
> + * Return 0 as controller IDLE
> + * Return a negative errno as controller ACTIVE
But why non-boolean again?
> + */
> +static int i2c_dw_is_controller_active(struct dw_i2c_dev *dev)
> +{
> + u32 status;
> +
> + regmap_read(dev->map, DW_IC_STATUS, &status);
> + if (!(status & DW_IC_STATUS_MASTER_ACTIVITY))
> + return 0;
> +
> + return regmap_read_poll_timeout(dev->map, DW_IC_STATUS, status,
> + !(status & DW_IC_STATUS_MASTER_ACTIVITY),
> + 1100, 20000);
> +}
...
> + /*
> + * This happens rarely (~1:500) and is hard to reproduce. Debug trace
> + * showed that IC_STATUS had value of 0x23 when STOP_DET occurred,
> + * if disable IC_ENABLE.ENABLE immediately that can result in
> + * IC_RAW_INTR_STAT.MASTER_ON_HOLD holding SCL low. Check if
> + * controller is still ACTIVE before disabling I2C.
> + */
> + if (i2c_dw_is_controller_active(dev))
> + dev_err(dev->dev, "controller active\n");
No, this is rarely we skip the error code returned. Either you find the
meaningful use of the returned error code, or change to boolean.
Personally I think the latter is what we need for now.
> /*
> * We must disable the adapter before returning and signaling the end
> * of the current transfer. Otherwise the hardware might continue
--
With Best Regards,
Andy Shevchenko
