Re: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev

Peter Chen
2016-09-08T12:28:21Z

On Thu, Sep 08, 2016 at 12:17:21PM +0200, Arnd Bergmann wrote:
> On Thursday, September 8, 2016 12:43:06 PM CEST Felipe Balbi wrote:
> > Arnd Bergmann <arnd@arndb.de> writes:
> > > On Thursday, September 8, 2016 11:29:04 AM CEST Felipe Balbi wrote:
> > >> > If we do that, we have to put child devices of the dwc3 devices into
> > >> > the platform glue, and it also breaks those dwc3 devices that don't
> > >> > have a parent driver.
> > >>
> > >> Well, this is easy to fix:
> > >>
> > >> if (dwc->dev->parent) {
> > >> dwc->sysdev = dwc->dev->parent;
> > >> } else {
> > >> dev_info(dwc->dev, "Please provide a glue layer!\n");
> > >> dwc->sysdev = dwc->dev;
> > >> }
> > >
> > > I don't understand. Do you mean we should have an extra level of
> > > stacking and splitting "static struct platform_driver dwc3_driver"
> > > in two so instead of
> > >
> > > "qcom,dwc3" -> "snps,dwc3" (usb_bus.sysdev) -> "xhci" (usb_bus.dev)
> > >
> > > we do this?
> > >
> > > "qcom,dwc3" -> "snps,dwc3" (usb_bus.sysdev) -> "dwc3-glue" -> "xhci" (usb_bus.dev)
> >
> > no
> >
> > If we have a parent device, use that as sysdev, otherwise use self as
> > sysdev.
>
> But there is often a parent device in DT, as the xhci device is
> attached to some internal bus that gets turned into a platform_device
> as well, so checking whether there is a parent will get the wrong
> device node.

>From my point, all platform and firmware information at dwc3 are
correct, so we don't need to change dwc3/core.c, only changing for
xhci-plat.c is ok.

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index ed56bf9..fd57c0d 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -145,6 +145,7 @@ static int xhci_plat_probe(struct platform_device *pdev)
struct clk *clk;
int ret;
int irq;
+ struct device *dev = &pdev->dev, *sysdev;

if (usb_disabled())
return -ENODEV;
@@ -155,6 +156,12 @@ static int xhci_plat_probe(struct platform_device *pdev)
if (irq < 0)
return -ENODEV;

+ if (dev->parent) {
+ sysdev = dev->parent;
+ } else {
+ sysdev = dev;
+ }
+
/* Try to set 64-bit DMA first */
if (WARN_ON(!pdev->dev.dma_mask))
/* Platform did not initialize dma_mask */
@@ -170,7 +177,8 @@ static int xhci_plat_probe(struct platform_device *pdev)
return ret;
}

- hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
+ hcd = __usb_create_hcd(driver, sysdev, &pdev->dev,
+ dev_name(&pdev->dev), NULL);
if (!hcd)
return -ENOMEM;

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index d2e3f65..563600b 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1118,7 +1118,7 @@ static int register_root_hub(struct usb_hcd *hcd)
/* Did the HC die before the root hub was registered? */
if (HCD_DEAD(hcd))
usb_hc_died (hcd); /* This time clean up */
- usb_dev->dev.of_node = parent_dev->of_node;
+ usb_dev->dev.of_node = parent_dev->sysdev->of_node;
}
mutex_unlock(&usb_bus_idr_lock);

At above changes, the root hub's of_node equals to xhci-hcd sysdev's
of_node, which is from firmware or from its parent (it is dwc3 core
device).

>
> > > That sounds a bit clumsy for the sake of consistency with PCI.
> > > The advantage is that xhci can always use the grandparent device
> > > as sysdev whenever it isn't probed through PCI or firmware
> > > itself, but the purpose of the dwc3-glue is otherwise questionable.
> > >
> > > How about adding a 'compatible="snps,dwc3-pci"' property for the dwc3
> > > device when that is created from the PCI driver and checking for that
> > > with the device property interface instead? If it's "snps,dwc3"
> > > we use the device itself while for "snps,dwc3-pci", we use the parent?
> >

For pci glue device, it is always the parent for dwc3 core device.
In your patch, you may not need to split pci or non-pci, just using
if (dev->parent).

> > Any reason why we wouldn't use e.g. dwc3-omap.dev as sysdev?
>
> That would be incompatible with the USB binding, as the sysdev
> is assumed to be a USB host controller with #address-cells=<1>
> and #size-cells=<0> in order to hold the child devices, for
> example:
>
> / {
> omap_dwc3_1: omap_dwc3_1@48880000 {
> compatible = "ti,dwc3";
> #address-cells = <1>;
> #size-cells = <1>;
> ranges;
> usb1: usb@48890000 {
> compatible = "snps,dwc3";
> reg = <0x48890000 0x17000>;
> #address-cells = <1>;
> #size-cells = <0>;
> interrupts = <GIC_SPI 71 IRQ_TYPE_LEVEL_HIGH>,
> <GIC_SPI 71 IRQ_TYPE_LEVEL_HIGH>,
> <GIC_SPI 72 IRQ_TYPE_LEVEL_HIGH>;
> interrupt-names = "peripheral",
> "host",
> "otg";
> phys = <&usb2_phy1>, <&usb3_phy1>;
> phy-names = "usb2-phy", "usb3-phy";
>
> hub@1 {
> compatible = "usb5e3,608";
> reg = <1>;
> #address-cells = <1>;
> #size-cells = <0>;
>
> ethernet@1 {
> compatible = "usb424,ec00";
> mac-address = [00 11 22 33 44 55];
> reg = <1>;
> };
> };
> };
> };
>

With my above changes, the hub of_node should be found since it is
child of root hub's of_node which is the dwc3's of_node.

> It's also the node that contains the "phys" properties and
> presumably other properties like "otg-rev", "maximum-speed"
> etc.
>

This information is described at dwc3 core device of_node, and be
handled at dwc3/core.c

--

Best Regards,
Peter Chen