Re: [PATCH 1/7] usb: dwc3: get "usb_phy" only if the platformindicates the presence of PHY

[Vivek Gautam]

Hi,


On Thu, Sep 12, 2013 at 4:34 PM, Roger Quadros <rogerq@xxxxxx> wrote:
> Hi,
>
> On 09/12/2013 01:47 PM, Vivek Gautam wrote:
>> On Thu, Sep 12, 2013 at 4:06 PM, Roger Quadros <rogerq@xxxxxx> wrote:
>>> Hi Kishon,
>>>
>>> On 09/02/2013 06:43 PM, Kishon Vijay Abraham I wrote:
>>>> There can be systems which does not have a external usb_phy, so get
>>>> usb_phy only if usb-phy property is added in the case of dt boot or if
>>>> platform_data indicates the presence of PHY. Also remove checking if
>>>> return value is -ENXIO since it's now changed to always enable usb_phy layer.
>>>>
>>>> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
>>>> ---
>>>>  drivers/usb/dwc3/Kconfig         |    1 +
>>>>  drivers/usb/dwc3/core.c          |   60 +++++++++++++++++---------------------
>>>>  drivers/usb/dwc3/platform_data.h |    1 +
>>>>  3 files changed, 28 insertions(+), 34 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
>>>> index f969ea2..cfc16dd 100644
>>>> --- a/drivers/usb/dwc3/Kconfig
>>>> +++ b/drivers/usb/dwc3/Kconfig
>>>> @@ -2,6 +2,7 @@ config USB_DWC3
>>>>       tristate "DesignWare USB3 DRD Core Support"
>>>>       depends on (USB || USB_GADGET) && GENERIC_HARDIRQS && HAS_DMA
>>>>       depends on EXTCON
>>>> +     select USB_PHY
>>>>       select USB_XHCI_PLATFORM if USB_SUPPORT && USB_XHCI_HCD
>>>>       help
>>>>         Say Y or M here if your system has a Dual Role SuperSpeed
>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>> index 474162e..428c29e 100644
>>>> --- a/drivers/usb/dwc3/core.c
>>>> +++ b/drivers/usb/dwc3/core.c
>>>> @@ -387,16 +387,38 @@ static int dwc3_probe(struct platform_device *pdev)
>>>>       if (node) {
>>>>               dwc->maximum_speed = of_usb_get_maximum_speed(node);
>>>>
>>>> -             dwc->usb2_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 0);
>>>> -             dwc->usb3_phy = devm_usb_get_phy_by_phandle(dev, "usb-phy", 1);
>>>> +             if (of_property_read_bool(node, "usb-phy")) {
>>>> +                     dwc->usb2_phy = devm_usb_get_phy_by_phandle(dev,
>>>> +                             "usb-phy", 0);
>>>> +                     if (IS_ERR(dwc->usb2_phy))
>>>> +                             return PTR_ERR(dwc->usb2_phy);
>>>> +                     dwc->usb3_phy = devm_usb_get_phy_by_phandle(dev,
>>>> +                             "usb-phy", 1);
>>>> +                     if (IS_ERR(dwc->usb3_phy))
>>>> +                             return PTR_ERR(dwc->usb3_phy);
>>>
>>> Some DWC3 instances use only usb2_phy. e.g. on DRA7 the 2nd dwc3 instance doesn't use usb3_phy.
>>> This needs to be a valid case and driver shouldn't error out.
>>
>> So, i think adding flexibility to DWC3 to have either
>> usb2-phy/usb3-phy or both of them seems to be valid point.
>> Any suggestions ?
>>
>
> For high speed operation we need only usb2_phy but for super speed we need both usb2_phy
> and usb3_phy.
>
> Why would a dwc3 controller use only usb3_phy? A USB3.0 interface has to be compatible with
> USB2.0 as well, no?

True and for that reason we need both UTMI+ interface as well as PIPE3
interface, right ?
But as also mentioned in the thread:
https://lkml.org/lkml/2013/9/12/181, on Samsung exynos5
architecturally same block is managing UTMI+ and PIPE3 interfaces,
which is handled by phy-samsung-usb3 driver and denoted by "usb3_phy:
usbphy@12100000" node in "arch/arm/boot/dts/exynos5250.dtsi".

So on exynos5250, DWC3 really needs just usb3-phy, which is compatible
for USB 2.0 as well.

>
> cheers,
> -roger
>



-- 
Best Regards
Vivek
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/