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Subject: Re: [PATCH 2/3] xhci: Add zhaoxin xHCI U1/U2 feature support
To:     Weitao Wang <WeitaoWang-oc@zhaoxin.com>,
        gregkh@linuxfoundation.org, mathias.nyman@intel.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     tonywwang@zhaoxin.com, weitaowang@zhaoxin.com
References: <20230420172130.375819-1-WeitaoWang-oc@zhaoxin.com>
 <20230420172130.375819-3-WeitaoWang-oc@zhaoxin.com>
From:   Sergei Shtylyov <sergei.shtylyov@gmail.com>
Message-ID: <c853436a-85c7-d0f8-0990-bc64977cbd47@gmail.com>
Date:   Thu, 20 Apr 2023 12:39:47 +0300
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On 4/20/23 8:21 PM, Weitao Wang wrote:

> Add U1/U2 feature support of xHCI for zhaoxin.
> 
> Signed-off-by: Weitao Wang <WeitaoWang-oc@zhaoxin.com>
[...]

> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 6307bae9cddf..730c0f68518d 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
[...]
> @@ -4938,6 +4938,27 @@ static int xhci_update_timeout_for_interface(struct xhci_hcd *xhci,
>  	return 0;
>  }
>  
> +static int xhci_check_zhaoxin_tier_policy(struct usb_device *udev,
> +		enum usb3_link_state state)
> +{
> +	struct usb_device *parent;
> +	unsigned int num_hubs;
> +
> +	/* Don't enable U1/U2 if the device is on an external hub. */
> +	for (parent = udev->parent, num_hubs = 0; parent->parent;
> +			parent = parent->parent)
> +		num_hubs++;
> +
> +	if (num_hubs < 1)
> +		return 0;
> +
> +	dev_dbg(&udev->dev, "Disabling U1/U2 link state for device"
> +			" below external hub.\n");
> +	dev_dbg(&udev->dev, "Plug device into root hub "
> +			"to decrease power consumption.\n");

   Please don't break up the message strings.

[...]
> @@ -4965,6 +4986,8 @@ static int xhci_check_tier_policy(struct xhci_hcd *xhci,
>  {
>  	if (xhci->quirks & XHCI_INTEL_HOST)
>  		return xhci_check_intel_tier_policy(udev, state);
> +	else if (xhci->quirks & XHCI_ZHAOXIN_HOST)

   *else* not needed after *return*.

> +		return xhci_check_zhaoxin_tier_policy(udev, state);
>  	else
>  		return 0;
>  }

MBR, Sergey