linux-kernel - Re: [PATCH v2 4/9] pinctrl: tegra-xusb: Add USB PHY support

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Date:	Mon, 25 Aug 2014 13:22:38 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Andrew Bresticker <abrestic@...omium.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Mikko Perttunen <mperttunen@...dia.com>
CC:	linux-tegra@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Jassi Brar <jassisinghbrar@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Grant Likely <grant.likely@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Arnd Bergmann <arnd@...db.de>,
	Kishon Vijay Abraham I <kishon@...com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 4/9] pinctrl: tegra-xusb: Add USB PHY support

On 08/18/2014 11:08 AM, Andrew Bresticker wrote:
> In addition to the PCIe and SATA PHYs, the XUSB pad controller also
> supports 3 UTMI, 2 HSIC, and 2 USB3 PHYs.  Each USB3 PHY uses a single
> PCIe or SATA lane and is mapped to one of the three UTMI ports.
>
> The xHCI controller will also send messages intended for the PHY driver,
> so request and listen for messages on the mailbox's PHY channel.

I'd like a review from Thierry here as the HW expert.

I need an ack from LinusW in order to take this pinctrl patch through 
the Tegra tree.

> diff --git a/drivers/pinctrl/pinctrl-tegra-xusb.c b/drivers/pinctrl/pinctrl-tegra-xusb.c

> +static int usb3_phy_power_on(struct phy *phy)
> +{
> +	struct tegra_xusb_padctl *padctl = phy_get_drvdata(phy);
> +	int port = usb3_phy_to_port(phy);
> +	int lane = padctl->usb3_ports[port].lane;
> +	u32 value, offset;
> +
> +	if (!is_pcie_or_sata_lane(lane)) {
> +		dev_err(padctl->dev, "USB3 PHY %d mapped to invalid lane: %d\n",
> +			port, lane);
> +		return -EINVAL;
> +	}

An aside: This implies that the SATA driver should be talking to this 
pinctrl driver and explicitly powering on the XUSB pins. However, the 
SATA driver doesn't depend on this series. I'm a bit confused how that 
works. Perhaps it's just by accident? Mikko, can you comment?

> +static int utmi_phy_to_port(struct phy *phy)
> +{
> +	struct tegra_xusb_padctl *padctl = phy_get_drvdata(phy);
> +	int i;
> +
> +	for (i = 0; i < TEGRA_XUSB_UTMI_PHYS; i++) {
> +		if (phy == padctl->phys[TEGRA_XUSB_PADCTL_UTMI_P0 + i])
> +			break;
> +	}
> +	BUG_ON(i == TEGRA_XUSB_UTMI_PHYS);

Can this be triggered by e.g. bad DT content? If so, returning an error 
would be nicer. The comment applies to other xxx_to_port() functions.

> @@ -896,6 +1933,22 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)

> +	for (i = 0; i < TEGRA_XUSB_USB3_PHYS; i++) {
> +		char prop[sizeof("nvidia,usb3-port-N-lane")];
> +		u32 lane;
> +
> +		sprintf(prop, "nvidia,usb3-port-%d-lane", i);
> +		if (!of_property_read_u32(pdev->dev.of_node, prop, &lane)) {
> +			if (!is_pcie_or_sata_lane(lane)) {
> +				err = -EINVAL;
> +				goto unregister;

It'd be nice to print a message so that the user/developer knows what's 
wrong with the DT.
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