Re: [PATCH v13 06/12] usb: xhci: use bus->sysdev for DMA configuration

Roger Quadros
2017-02-15T10:12:12Z

+Felipe,

On 15/02/17 10:51, Peter Chen wrote:
> On Wed, Feb 15, 2017 at 10:18:03AM +0200, Roger Quadros wrote:
>> Peter,
>>
>> On 15/02/17 03:35, Peter Chen wrote:
>>> On Tue, Feb 14, 2017 at 01:58:40PM +0100, Arnd Bergmann wrote:
>>>> On Tue, Feb 14, 2017 at 1:26 PM, Roger Quadros <rogerq@ti.com> wrote:
>>>>> On 14/02/17 13:44, Arnd Bergmann wrote:
>>>>>> On Tue, Feb 14, 2017 at 11:36 AM, Roger Quadros <rogerq@ti.com> wrote:
>>>>
>>>>>>> Why are we using sysdev to read DT property? We should be using the
>>>>>>> XHCI device (&pdev->dev) here, no?
>>>>>>
>>>>>> If I remember correctly, this is one of the cases where pdev does not
>>>>>> have a device node attached to it because it was created by the driver
>>>>>> of the parent device on the fly in case of dwc3. When you have a pure xhci
>>>>>> device in DT, the two pointers are the same.
>>>>>
>>>>> From drivers/usb/dwc3/host.c
>>>>>
>>>>>> if (dwc->usb3_lpm_capable) {
>>>>>> props[0].name = "usb3-lpm-capable";
>>>>>> ret = platform_device_add_properties(xhci, props);
>>>>>> if (ret) {
>>>>>> dev_err(dwc->dev, "failed to add properties to xHCI\n");
>>>>>> goto err1;
>>>>>> }
>>>>>> }
>>>>>
>>>>> So it is setting the usb3-lpm-capable property into the xhci platform device
>>>>> and we should be reading the property from there.
>>>
>>> Why dwc3 needs another "snps,usb3_lpm_capable"? Why not using
>>> "usb3-lpm-capable" at firmware directly?
>>
>> dwc3 is not setting "snps,usb3_lpm_capable" but "usb3-lpm-capable" for the
>> xhci platform device.
>>
>> What did you mean by firmware? Did you mean something like BIOS?
>> At least TI platforms don't use any firmware like BIOS. So dwc3 driver
>> needs to create a platform device for xhci on the fly and set the DT properties.
>>
>
> By readying code, the dwc3 calls dwc3_get_properties to set
> dwc->usb3_lpm_capable, and at dwc3/host.c, it sets property
> "usb3-lpm-capable" according to this flag, why not let common
> code xhci-plat.c to get this property from sysdev which is DT
> nodes for dwc3?
>

Felipe, any comments?

--
cheers,
-roger