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

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Message-ID: <72263b67-6b33-de44-d568-a967ee3503ae@ti.com>
Date:   Thu, 8 Sep 2016 15:59:19 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Peter Chen <hzpeterchen@...il.com>, Arnd Bergmann <arnd@...db.de>
CC:     Felipe Balbi <balbi@...nel.org>, Leo Li <pku.leo@...il.com>,
        Russell King - ARM Linux <linux@....linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Sekhar Nori <nsekhar@...com>,
        lkml <linux-kernel@...r.kernel.org>,
        Stuart Yoder <stuart.yoder@....com>,
        Scott Wood <oss@...error.net>,
        David Fisher <david.fisher1@...opsys.com>,
        "Thang Q. Nguyen" <tqnguyen@....com>,
        Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] usb: dwc3: host: inherit dma configuration from parent
 dev

On 09/08/2016 03:28 PM, Peter Chen wrote:
> 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@...db.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;
> +	}
> +

Shouldn't we be more careful with that?

armada-375.dtsi

	soc {
		compatible = "marvell,armada375-mbus", "simple-bus";

		internal-regs {
			compatible = "simple-bus";

			usb3@...00 {
				compatible = "marvell,armada-375-xhci";
				reg = <0x58000 0x20000>,<0x5b880 0x80>;
				interrupts = <GIC_SPI 16 IRQ_TYPE_LEVEL_HIGH>;
				clocks = <&gateclk 16>;
				phys = <&usbcluster PHY_TYPE_USB3>;
				phy-names = "usb";
				status = "disabled";
			};


What will be the parent dev in above case?

-- 
regards,
-grygorii