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Date:   Tue, 31 May 2022 17:56:05 +0530
From:   Pavan Kondeti <quic_pkondeti@quicinc.com>
To:     Harsh Agarwal <quic_harshq@quicinc.com>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
        Felipe Balbi <balbi@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        <linux-usb@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <quic_pkondeti@quicinc.com>,
        <quic_ppratap@quicinc.com>, <quic_jackp@quicinc.com>
Subject: Re: [PATCH 3/3] usb: dwc3: Refactor PHY logic to support Multiport
 Controller
Message-ID: <20220531122605.GA14607@hu-pkondeti-hyd.qualcomm.com>
References: <1653985217-20953-1-git-send-email-quic_harshq@quicinc.com>
 <1653985217-20953-4-git-send-email-quic_harshq@quicinc.com>
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In-Reply-To: <1653985217-20953-4-git-send-email-quic_harshq@quicinc.com>
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Hi Harsh,

On Tue, May 31, 2022 at 01:50:17PM +0530, Harsh Agarwal wrote:
> Currently the DWC3 driver supports only single port controller
> which requires at most 2 PHYs ie HS and SS PHYs.
> 
> But some SOCs have a "multiport" USB DWC3 controller where a
> single controller supports multiple ports and each port have
> their own PHYs. Refactor PHY logic to support the same.
> 
> Signed-off-by: Harsh Agarwal <quic_harshq@quicinc.com>
> ---
>  drivers/usb/dwc3/core.c   | 400 +++++++++++++++++++++++++++++++++-------------
>  drivers/usb/dwc3/core.h   |  12 +-
>  drivers/usb/dwc3/drd.c    |  16 +-
>  drivers/usb/dwc3/gadget.c |   4 +-
>  4 files changed, 305 insertions(+), 127 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 5734219..5cc799e 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -120,7 +120,7 @@ static void __dwc3_set_mode(struct work_struct *work)
>  {
>  	struct dwc3 *dwc = work_to_dwc(work);
>  	unsigned long flags;
> -	int ret;
> +	int i, ret;
>  	u32 reg;
>  

<snip>

> -static int dwc3_core_get_phy(struct dwc3 *dwc)
> +static struct usb_phy *dwc3_core_get_phy_by_handle_with_node(struct device *dev,
> +	const char *phandle, u8 index, struct device_node *lookup_node)
> +{
> +	struct device_node *node;
> +	struct usb_phy	*phy;
> +
> +	node = of_parse_phandle(lookup_node, phandle, index);
> +	if (!node) {
> +		dev_err(dev, "failed to get %s phandle in %pOF node\n", phandle,
> +			dev->of_node);
> +		return ERR_PTR(-ENODEV);
> +	}
> +	phy = devm_usb_get_phy_by_node(dev, node, NULL);
> +	of_node_put(node);
> +	return phy;
> +}

Remove this function definition, since we moved this to PHY library.

> +
> +static int dwc3_count_phys(struct dwc3 *dwc, struct device_node *lookup_node)
> +{
> +	int count;
> +
> +	count = of_count_phandle_with_args(lookup_node, "phys", NULL);
> +
> +	if (count == -ENOENT)
> +		count = of_count_phandle_with_args(lookup_node, "usb-phy", NULL);
> +
> +	if (count == 1) {
> +		dwc->num_usb2_phy++;
> +	} else if (count == 2) {
> +		dwc->num_usb2_phy++;
> +		dwc->num_usb3_phy++;
> +	} else {
> +		return count;
> +	}
> +	return 0;
> +}
> +
> +static int dwc3_extract_num_phys(struct dwc3 *dwc)
> +{
> +	struct device_node	*ports, *port;
> +	int			ret;
> +
> +	/* Find if any "multiport" child is present inside DWC3*/
> +	for_each_available_child_of_node(dwc->dev->of_node, ports) {
> +		if (!strcmp(ports->name, "multiport"))
> +			break;
> +	}
> +	if (!ports) {
> +		dwc->num_usb2_phy = 1;
> +		dwc->num_usb3_phy = 1;
> +	} else {
> +		for_each_available_child_of_node(ports, port) {
> +			ret  = dwc3_count_phys(dwc, port);
> +			if (ret)
> +				return ret;

If you break the loop, you have to call of_node_put() explicitly.

> +		}
> +	}
> +	dev_info(dwc->dev, "Num of HS and SS PHY are %u %u\n", dwc->num_usb2_phy,
> +									dwc->num_usb3_phy);

If I declare the multiport node don't specify any phys for any of the ports,
we end up coming here with dwc->num_usb2_phy = dwc->num_usb3_phy = 0. That is
a problem since we access dwc->usb2_phy[0] directly. Can we bail out in that
case?

> +
> +	dwc->usb2_phy = devm_kzalloc(dwc->dev,
> +		sizeof(*dwc->usb2_phy) * dwc->num_usb2_phy, GFP_KERNEL);
> +	if (!dwc->usb2_phy)
> +		return -ENOMEM;
> +
> +	dwc->usb3_phy = devm_kzalloc(dwc->dev,
> +		sizeof(*dwc->usb3_phy) * dwc->num_usb3_phy, GFP_KERNEL);
> +	if (!dwc->usb3_phy)
> +		return -ENOMEM;
> +
> +	dwc->usb2_generic_phy = devm_kzalloc(dwc->dev,
> +		sizeof(*dwc->usb2_generic_phy) * dwc->num_usb2_phy, GFP_KERNEL);
> +	if (!dwc->usb2_generic_phy)
> +		return -ENOMEM;
> +
> +	dwc->usb3_generic_phy = devm_kzalloc(dwc->dev,
> +		sizeof(*dwc->usb3_generic_phy) * dwc->num_usb3_phy, GFP_KERNEL);
> +	if (!dwc->usb3_generic_phy)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int dwc3_core_get_phy_by_node(struct dwc3 *dwc,
> +		struct device_node *lookup_node, int i)
>  {
>  	struct device		*dev = dwc->dev;
> -	struct device_node	*node = dev->of_node;
> -	int ret;
> +	int			ret;
>  
> -	if (node) {
> -		dwc->usb2_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 0);
> -		dwc->usb3_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 1);
> +	if (lookup_node) {
> +		dwc->usb2_phy[i] = devm_of_usb_get_phy_by_phandle(dev,
> +								"usb-phy", 0, lookup_node);
> +		dwc->usb3_phy[i] = devm_of_usb_get_phy_by_phandle(dev,
> +								"usb-phy", 1, lookup_node);
>  	} else {
> -		dwc->usb2_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> -		dwc->usb3_phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB3);
> +		dwc->usb2_phy[i] = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> +		dwc->usb3_phy[i] = devm_usb_get_phy(dev, USB_PHY_TYPE_USB3);
>  	}
>  
> -	if (IS_ERR(dwc->usb2_phy)) {
> -		ret = PTR_ERR(dwc->usb2_phy);
> +	if (IS_ERR(dwc->usb2_phy[i])) {
> +		ret = PTR_ERR(dwc->usb2_phy[i]);
>  		if (ret == -ENXIO || ret == -ENODEV)
> -			dwc->usb2_phy = NULL;
> +			dwc->usb2_phy[i] = NULL;
>  		else
>  			return dev_err_probe(dev, ret, "no usb2 phy configured\n");
>  	}
>  
> -	if (IS_ERR(dwc->usb3_phy)) {
> -		ret = PTR_ERR(dwc->usb3_phy);
> +	if (IS_ERR(dwc->usb3_phy[i])) {
> +		ret = PTR_ERR(dwc->usb3_phy[i]);
>  		if (ret == -ENXIO || ret == -ENODEV)
> -			dwc->usb3_phy = NULL;
> +			dwc->usb3_phy[i] = NULL;
>  		else
>  			return dev_err_probe(dev, ret, "no usb3 phy configured\n");
>  	}
>  
> -	dwc->usb2_generic_phy = devm_phy_get(dev, "usb2-phy");
> -	if (IS_ERR(dwc->usb2_generic_phy)) {
> -		ret = PTR_ERR(dwc->usb2_generic_phy);
> -		if (ret == -ENOSYS || ret == -ENODEV)
> -			dwc->usb2_generic_phy = NULL;
> +	dwc->usb2_generic_phy[i] = devm_of_phy_get(dev, lookup_node, "usb2-phy");
> +	if (IS_ERR(dwc->usb2_generic_phy[i])) {
> +		ret = PTR_ERR(dwc->usb2_generic_phy[i]);
> +		if (ret == -ENODEV)
> +			dwc->usb2_generic_phy[i] = NULL;
>  		else
>  			return dev_err_probe(dev, ret, "no usb2 phy configured\n");
>  	}
>  
> -	dwc->usb3_generic_phy = devm_phy_get(dev, "usb3-phy");
> -	if (IS_ERR(dwc->usb3_generic_phy)) {
> -		ret = PTR_ERR(dwc->usb3_generic_phy);
> -		if (ret == -ENOSYS || ret == -ENODEV)
> -			dwc->usb3_generic_phy = NULL;
> +	dwc->usb3_generic_phy[i] = devm_of_phy_get(dev, lookup_node, "usb3-phy");
> +	if (IS_ERR(dwc->usb3_generic_phy[i])) {
> +		ret = PTR_ERR(dwc->usb3_generic_phy[i]);
> +		if (ret == -ENODEV)
> +			dwc->usb3_generic_phy[i] = NULL;
>  		else
>  			return dev_err_probe(dev, ret, "no usb3 phy configured\n");
>  	}
> +	return 0;
> +}
> +
> +static int dwc3_core_get_phy(struct dwc3 *dwc)
> +{
> +	struct device		*dev = dwc->dev;
> +	struct device_node	*node = dev->of_node;
> +	struct device_node	*ports, *port;
> +	int ret, i = 0;
> +
> +	ret = dwc3_extract_num_phys(dwc);
> +	if (ret) {
> +		dev_err(dwc->dev, "Unable to extract number of PHYs\n");
> +		return ret;
> +	}
> +
> +	/* Find if any "multiport" child is present inside DWC3*/
> +	for_each_available_child_of_node(node, ports) {
> +		if (!strcmp(ports->name, "multiport"))
> +			break;
> +	}
> +
> +	if (!ports) {
> +		ret = dwc3_core_get_phy_by_node(dwc, node, 0);
> +		if (ret)
> +			return ret;
> +	} else {
> +		for_each_available_child_of_node(ports, port) {
> +			ret = dwc3_core_get_phy_by_node(dwc, port, i);
> +			if (ret)
> +				return ret;
> +			i++;
> +		}
> +	}
>  
How does this work actually for a case where I have 4 ports with hs_phy=4 and
ss_phy=2. Here we end up calling i = {0, 1, 2, 3} and accessing un-allocated
ss phy instances in dwc3_core_get_phy_by_node(). you should also handle the
case where first two ports are HS only and last two ports are both HS and SS.

Thanks,
Pavan