linux-kernel - Re: [PATCH 5/5] usb: typec: ucsi: Clear UCSI_CCI_RESET

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Date: Fri, 22 Mar 2024 12:06:17 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: "Christian A. Ehrhardt" <lk@...e.de>
Cc: linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Prashant Malani <pmalani@...omium.org>,
	Jameson Thies <jthies@...gle.com>,
	Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	Samuel Čavoj <samuel@...oj.net>,
	linux-usb@...r.kernel.org, Kenneth Crudup <kenny@...ix.com>
Subject: Re: [PATCH 5/5] usb: typec: ucsi: Clear UCSI_CCI_RESET_COMPLETE
 before reset

On Wed, Mar 20, 2024 at 08:39:26AM +0100, Christian A. Ehrhardt wrote:
> Check the UCSI_CCI_RESET_COMPLETE complete flag before starting
> another reset. Use a UCSI_SET_NOTIFICATION_ENABLE command to clear
> the flag if it is set.
> 
> Signed-off-by: Christian A. Ehrhardt <lk@...e.de>

Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
>  drivers/usb/typec/ucsi/ucsi.c | 36 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 63f340dbd867..85e507df7fa8 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1264,13 +1264,47 @@ static int ucsi_reset_connector(struct ucsi_connector *con, bool hard)
>  
>  static int ucsi_reset_ppm(struct ucsi *ucsi)
>  {
> -	u64 command = UCSI_PPM_RESET;
> +	u64 command;
>  	unsigned long tmo;
>  	u32 cci;
>  	int ret;
>  
>  	mutex_lock(&ucsi->ppm_lock);
>  
> +	ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
> +	if (ret < 0)
> +		goto out;
> +
> +	/*
> +	 * If UCSI_CCI_RESET_COMPLETE is already set we must clear
> +	 * the flag before we start another reset. Send a
> +	 * UCSI_SET_NOTIFICATION_ENABLE command to achieve this.
> +	 * Ignore a timeout and try the reset anyway if this fails.
> +	 */
> +	if (cci & UCSI_CCI_RESET_COMPLETE) {
> +		command = UCSI_SET_NOTIFICATION_ENABLE;
> +		ret = ucsi->ops->async_write(ucsi, UCSI_CONTROL, &command,
> +					     sizeof(command));
> +		if (ret < 0)
> +			goto out;
> +
> +		tmo = jiffies + msecs_to_jiffies(UCSI_TIMEOUT_MS);
> +		do {
> +			ret = ucsi->ops->read(ucsi, UCSI_CCI,
> +					      &cci, sizeof(cci));
> +			if (ret < 0)
> +				goto out;
> +			if (cci & UCSI_CCI_COMMAND_COMPLETE)
> +				break;
> +			if (time_is_before_jiffies(tmo))
> +				break;
> +			msleep(20);
> +		} while (1);
> +
> +		WARN_ON(cci & UCSI_CCI_RESET_COMPLETE);
> +	}
> +
> +	command = UCSI_PPM_RESET;
>  	ret = ucsi->ops->async_write(ucsi, UCSI_CONTROL, &command,
>  				     sizeof(command));
>  	if (ret < 0)
> -- 
> 2.40.1

-- 
heikki