linux-kernel - Re: [PATCH v11] i2c: designware: fix controller is holding SCL low while ENABLE bit is disabled

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Message-ID: <CAHp75Vdbr5sJejwfkxYrgkdNMMZV+D5w1mipTxz=R+EkEUrA0w@mail.gmail.com>
Date: Fri, 13 Sep 2024 10:40:50 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Kimriver Liu <kimriver.liu@...ngine.com>
Cc: jarkko.nikula@...ux.intel.com, andriy.shevchenko@...ux.intel.com, 
	mika.westerberg@...ux.intel.com, jsd@...ihalf.com, andi.shyti@...nel.org, 
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Andy Shevchenko <andy@...nel.org>
Subject: Re: [PATCH v11] i2c: designware: fix controller is holding SCL low
 while ENABLE bit is disabled

On Fri, Sep 13, 2024 at 6:35 AM Kimriver Liu <kimriver.liu@...ngine.com> wrote:
>
> It was observed that issuing the ABORT bit (IC_ENABLE[1]) will not
> work when IC_ENABLE is already disabled.
>
> Check if the ENABLE bit (IC_ENABLE[0]) is disabled when the controller
> is holding SCL low. If the ENABLE bit is disabled, the software needs
> to enable it before trying to issue the 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 fixes the issue where the controller cannot be disabled
> while SCL is held low if the ENABLE bit is already disabled.

...

> +                       /*Set ENABLE bit before setting ABORT*/

Missing spaces

...

> +/*
> + * This function waits controller idling before disabling I2C

waits for controller

> + * 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:

> + * False when controller is in IDLE state.
> + * True when controller is in ACTIVE state.

Yeah, I know that this is a copy of what I suggested, but if we going
to amend, these should be with definite article

 * False when the controller is in the IDLE state.
 * True when the controller is in the ACTIVE state.

> + */

...

> +       return regmap_read_poll_timeout(dev->map, DW_IC_STATUS, status,
> +                                      !(status & DW_IC_STATUS_MASTER_ACTIVITY),
> +                                      1100, 20000) != 0;

You broke the indentation again.

-- 
With Best Regards,
Andy Shevchenko