Subject: [PATCH v4 3/4] usb: ohci-exynos: Add facility to use phy provided by the generic phy framework

From: [email-masked] (Tomasz Figa)
Date: Thu, 01 May 2014 19:16:04 +0200

Hi Vivek,

Please see my comments inline.

On 30.04.2014 07:19, Vivek Gautam wrote:
> Add support to consume phy provided by Generic phy framework.
> Keeping the support for older usb-phy intact right now, in order
> to prevent any functionality break in absence of relevant
> device tree side change for ohci-exynos.
> Once we move to new phy in the device nodes for ohci, we can
> remove the support for older phys.
>
> Signed-off-by: Vivek Gautam <[email-masked]>
> Cc: Jingoo Han <[email-masked]>
> Cc: Alan Stern <[email-masked]>
> ---
>
> Changes from v3:
>   - Calling usb_phy_shutdown() when exynos_ohci_phy_enable() is failing.
>   - Made exynos_ohci_phy_disable() return void, since its return value
>     did not serve any purpose.
>   - Calling clk_disable_unprepare() in exynos_ohci_resume() when
>     exynos_ohci_phy_enable() is failed.
>
>   .../devicetree/bindings/usb/exynos-usb.txt         |   19 +++
>   drivers/usb/host/ohci-exynos.c                     |  128 +++++++++++++++++---
>   2 files changed, 132 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/usb/exynos-usb.txt b/Documentation/devicetree/bindings/usb/exynos-usb.txt
> index d967ba1..a90c973 100644
> --- a/Documentation/devicetree/bindings/usb/exynos-usb.txt
> +++ b/Documentation/devicetree/bindings/usb/exynos-usb.txt
> @@ -38,6 +38,15 @@ Required properties:
>    - interrupts: interrupt number to the cpu.
>    - clocks: from common clock binding: handle to usb clock.
>    - clock-names: from common clock binding: Shall be "usbhost".
> + - port: if in the SoC there are OHCI phys, they should be listed here.
> +   One phy per port. Each port should have following entries:
> +	- reg: port number on OHCI controller, e.g
> +	       On Exynos5250, port 0 is USB2.0 otg phy
> +			      port 1 is HSIC phy0
> +			      port 2 is HSIC phy1
> +	- phys: from the *Generic PHY* bindings, specifying phy used by port.
> +	- phy-names: from the *Generic PHY* bindings, specifying name of phy
> +		     used by the port.

I think you don't need this property for this binding, as the PHYs are 
being requested by indices (in fact only index 0 is used).

>
>   Example:
>   	usb at 12120000 {
> @@ -47,6 +56,16 @@ Example:
>
>   		clocks = <&clock 285>;
>   		clock-names = "usbhost";
> +
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		port at 0 {
> +		    reg = <0>;
> +		    phys = <&usb2phy 1>;
> +		    phy-names = "host";

Ditto.

> +		    status = "disabled";
> +		};
> +
>   	};
>
>   DWC3
> diff --git a/drivers/usb/host/ohci-exynos.c b/drivers/usb/host/ohci-exynos.c
> index 05f00e3..f90bf9a 100644
> --- a/drivers/usb/host/ohci-exynos.c
> +++ b/drivers/usb/host/ohci-exynos.c
> @@ -18,6 +18,7 @@
>   #include <linux/module.h>
>   #include <linux/of.h>
>   #include <linux/platform_device.h>
> +#include <linux/phy/phy.h>
>   #include <linux/usb/phy.h>
>   #include <linux/usb/samsung_usb_phy.h>
>   #include <linux/usb.h>
> @@ -33,28 +34,122 @@ static struct hc_driver __read_mostly exynos_ohci_hc_driver;
>
>   #define to_exynos_ohci(hcd) (struct exynos_ohci_hcd *)(hcd_to_ohci(hcd)->priv)
>
> +#define PHY_NUMBER 3

nit: A blank line would be nice here to separate from the struct below.

By the way, doesn't the number of PHY ports depend on platform? Of 
course right now the driver supports only Exynos >= 4210 SoCs with the 
generic PHY interface, so it might be changed in further patches.

>   struct exynos_ohci_hcd {
>   	struct clk *clk;
>   	struct usb_phy *phy;
>   	struct usb_otg *otg;
> +	struct phy *phy_g[PHY_NUMBER];
>   };
>
> -static void exynos_ohci_phy_enable(struct device *dev)
> +static int exynos_ohci_get_phy(struct device *dev,
> +				struct exynos_ohci_hcd *exynos_ohci)
> +{
> +	struct device_node *child;
> +	struct phy *phy;
> +	int phy_number;
> +	int ret = 0;
> +
> +	exynos_ohci->phy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
> +	if (IS_ERR(exynos_ohci->phy)) {
> +		ret = PTR_ERR(exynos_ohci->phy);
> +		/* This is the case when PHY config is disabled */
> +		if (ret == -ENXIO || ret == -ENODEV) {
> +			dev_dbg(dev, "Failed to get usb2 phy\n");
> +			exynos_ohci->phy = NULL;

I think you should keep this an ERR_PTR() and just use IS_ERR() check 
further in the driver instead of checking for NULL.

> +			ret = 0;

Do you need to set ret to 0 here? The code for getting generic PHYs will 
either leave it unchanged when there are no port nodes defined or 
overwrite it with value returned by of_property_read_u32(). In the first 
case, an error code should be returned, not zero, as the driver was 
unable to get any PHY.

> +		} else if (ret == -EPROBE_DEFER) {

I think you could merge this case with the else clause below, as most 
driver do. Moreover, since the only thing done after the fail_phy label 
is returning the error code, you could just immediately return from 
here. So the whole block of code would end up like this:

	if (IS_ERR(exynos_ohci->phy)) {
		ret = PTR_ERR(exynos_ohci->phy);
		if (ret != -ENXIO && ret != -ENODEV) {
			dev_err(dev, "no usb2 phy configured\n");
			return ret;
		}
		dev_dbg(dev, "Failed to get usb2 phy\n");
		exynos_ohci->phy = NULL;
	} else {
		exynos_ohci->otg = exynos_ohci->phy->otg;
	}

> +			goto fail_phy;
> +		} else {
> +			dev_err(dev, "no usb2 phy configured\n");
> +			goto fail_phy;
> +		}
> +	} else {
> +		exynos_ohci->otg = exynos_ohci->phy->otg;
> +	}
> +
> +	/* Getting generic phy:

CodingStyle: Multi-line comments should begin and end with a single 
empty line:

	/*
	 * Getting generic phy:
	 * ...
	 */

also nit: s/phy/PHY/

> +	 * We are keeping both types of phys as a part of transiting OHCI
> +	 * to generic phy framework, so that in absence of supporting dts
> +	 * changes the functionality doesn't break.
> +	 * Once we move the ohci dt nodes to use new generic phys,
> +	 * we can remove support for older PHY in this driver.

Well, this is not entirely true. The problem here is not caused by 
existing DTS files, but rather a chance that there are existing devices 
using DTB files built from them. So to remove the support for old 
bindings, we need to make sure that such devices have their DTBs updated 
to ones built from new DTS.

> +	 */
> +	for_each_available_child_of_node(dev->of_node, child) {
> +		ret = of_property_read_u32(child, "reg", &phy_number);
> +		if (ret) {
> +			dev_err(dev, "Failed to parse device tree\n");
> +			of_node_put(child);
> +			goto fail_phy;

Why not just return ret here?

> +		}

nit: Blank line here would be nice.

> +		if (phy_number >= PHY_NUMBER) {
> +			dev_err(dev, "Invalid number of PHYs\n");
> +			of_node_put(child);
> +			ret = -EINVAL;
> +			goto fail_phy;

What about just return -EINVAL;

> +		}

nit: Here too.

> +		phy = devm_of_phy_get(dev, child, 0);
> +		of_node_put(child);
> +		if (IS_ERR(phy)) {
> +			ret = PTR_ERR(phy);
> +			/* This is the case when PHY config is disabled */
> +			if (ret == -ENOSYS || ret == -ENODEV) {
> +				dev_dbg(dev, "Failed to get usb2 phy\n");
> +				phy = NCould you lULL;
> +				ret = 0;
> +			} else if (ret == -EPROBE_DEFER) {
> +				goto fail_phy;
> +			} else {
> +				dev_err(dev, "no usb2 phy configured\n");
> +				goto fail_phy;
> +			}
> +		}

Similar comments to this block apply as for the block getting legacy USB 
PHY.

> +		exynos_ohci->phy_g[phy_number] = phy;
> +	}
> +
> +fail_phy:
> +	return ret;
> +}
> +
> +static int exynos_ohci_phy_enable(struct device *dev)
>   {
>   	struct usb_hcd *hcd = dev_get_drvdata(dev);
>   	struct exynos_ohci_hcd *exynos_ohci = to_exynos_ohci(hcd);
> +	int i;
> +	int ret = 0;
>
> -	if (exynos_ohci->phy)
> -		usb_phy_init(exynos_ohci->phy);
> +	if (exynos_ohci->phy) {

!IS_ERR() should be used to check for validity.

> +		ret = usb_phy_init(exynos_ohci->phy);
> +		if (ret)
> +			return ret;

IMHO a simple return usb_phy_init(...) could be used here, if we are 
using the legacy PHY interface.

> +	}
> +
> +	for (i = 0; ret == 0 && i < PHY_NUMBER; i++)
> +		if (exynos_ohci->phy_g[i])

!IS_ERR(). Just make sure that the array is initialized with an 
ERR_PTR() with some error code, (-ENODEV) probably

> +			ret = phy_power_on(exynos_ohci->phy_g[i]);
> +	if (ret) {
> +		for (i--; i >= 0; i--)
> +			if (exynos_ohci->phy_g[i])

Ditto.

> +				phy_power_off(exynos_ohci->phy_g[i]);
> +		if (exynos_ohci->phy)
> +			usb_phy_shutdown(exynos_ohci->phy);

I don't think handling of legacy PHY is needed here. I don't think we 
can have both legacy and generic PHY used at the same time.

> +	}
> +
> +	return ret;
>   }
>
>   static void exynos_ohci_phy_disable(struct device *dev)
>   {
>   	struct usb_hcd *hcd = dev_get_drvdata(dev);
>   	struct exynos_ohci_hcd *exynos_ohci = to_exynos_ohci(hcd);
> +	int i;
>
>   	if (exynos_ohci->phy)
>   		usb_phy_shutdown(exynos_ohci->phy);
> +
> +	for (i = 0; i < PHY_NUMBER; i++)
> +		if (exynos_ohci->phy_g[i])

!IS_ERR()

Best regards,
Tomasz