linux-kernel - Re: [PATCH v4 1/2] platform/chrome: cros_ec

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Date:   Fri, 18 Aug 2023 17:01:51 +0000
From:   Prashant Malani <pmalani@...omium.org>
To:     Utkarsh Patel <utkarsh.h.patel@...el.com>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        heikki.krogerus@...ux.intel.com, bleung@...omium.org
Subject: Re: [PATCH v4 1/2] platform/chrome: cros_ec_typec: Configure Retimer
 cable type

Hi Utkarsh,

Sorry I was out on leave, so didnt get to this earlier.


On Jul 17 19:47, Utkarsh Patel wrote:
>  
> +/**
> + * cros_typec_get_cable_vdo() - Get Cable VDO of the connected cable
> + * @port: Type-C port data
> + * @svid: Standard or Vendor ID to match
> + *
> + * Returns the Cable VDO if match is found and returns 0 if match is not found.
> + */
> +static int cros_typec_get_cable_vdo(struct cros_typec_port *port, u16 svid)
return type should be u32.

> +{
> +	struct list_head *head = &port->plug_mode_list;
> +	struct cros_typec_altmode_node *node;
> +	u32 ret = 0;
> +
> +	list_for_each_entry(node, head, list) {
> +		if (node->amode->svid == svid)
> +			return node->amode->vdo;
> +	}
> +
> +	return ret;
> +}
> +
>  /*
>   * Spoof the VDOs that were likely communicated by the partner for TBT alt
>   * mode.
> @@ -432,6 +453,9 @@ static int cros_typec_enable_tbt(struct cros_typec_data *typec,
>  
>  	/* Cable Discover Mode VDO */
>  	data.cable_mode = TBT_MODE;
> +
> +	data.cable_mode |= cros_typec_get_cable_vdo(port, USB_TYPEC_TBT_SID);
> +
>  	data.cable_mode |= TBT_SET_CABLE_SPEED(pd_ctrl->cable_speed);
>  
>  	if (pd_ctrl->control_flags & USB_PD_CTRL_OPTICAL_CABLE)
> @@ -522,8 +546,10 @@ static int cros_typec_enable_usb4(struct cros_typec_data *typec,
>  	/* Cable Type */
>  	if (pd_ctrl->control_flags & USB_PD_CTRL_OPTICAL_CABLE)
>  		data.eudo |= EUDO_CABLE_TYPE_OPTICAL << EUDO_CABLE_TYPE_SHIFT;
> -	else if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_CABLE)
> +	else if (cros_typec_get_cable_vdo(port, USB_TYPEC_TBT_SID) & TBT_CABLE_RETIMER)
>  		data.eudo |= EUDO_CABLE_TYPE_RE_TIMER << EUDO_CABLE_TYPE_SHIFT;
We shouldn't need to call cros_typec_get_cable_vdo more than once. Either call it once earlier
when you are crafting the data.cable_mode member and then re-use that variable here. Or don't
call it there and just call it here.

> +	else if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_CABLE)
> +		data.eudo |= EUDO_CABLE_TYPE_RE_DRIVER << EUDO_CABLE_TYPE_SHIFT;
>  
>  	data.active_link_training = !!(pd_ctrl->control_flags &
>  				       USB_PD_CTRL_ACTIVE_LINK_UNIDIR);
> -- 
> 2.25.1
>