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SubjectRe: [PATCH v2 3/5] usb: dwc2: Add generic PHY framework support for dwc2 usb controler platform driver.
Hi Paul:

Thank you for replying.

On 2014/12/6 3:04, Paul Zimmerman wrote:
>> From: Yunzhi Li [mailto:lyz@rock-chips.com]
>> Sent: Friday, December 05, 2014 4:52 AM
>>
>> Get PHY parameters from devicetree and power off usb PHY during
>> system suspend.
>>
>> Signed-off-by: Yunzhi Li <lyz@rock-chips.com>
>> ---
>>
>> drivers/usb/dwc2/gadget.c | 33 ++++++++++++---------------------
>> drivers/usb/dwc2/platform.c | 34 ++++++++++++++++++++++++++++++++++
>> 2 files changed, 46 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>> index 200168e..2601c61 100644
>> --- a/drivers/usb/dwc2/gadget.c
>> +++ b/drivers/usb/dwc2/gadget.c
>> [...]
>>
>> /*
>> - * Attempt to find a generic PHY, then look for an old style
>> - * USB PHY, finally fall back to pdata
>> + * If platform probe couldn't find a generic PHY or an old style
>> + * USB PHY, fall back to pdata
>> */
>> - phy = devm_phy_get(dev, "usb2-phy");
>> - if (IS_ERR(phy)) {
>> - uphy = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
>> - if (IS_ERR(uphy)) {
>> - /* Fallback for pdata */
>> - plat = dev_get_platdata(dev);
>> - if (!plat) {
>> - dev_err(dev,
>> - "no platform data or transceiver defined\n");
>> - return -EPROBE_DEFER;
>> - }
>> - hsotg->plat = plat;
>> - } else
>> - hsotg->uphy = uphy;
>> - } else {
>> - hsotg->phy = phy;
>> + if (IS_ERR_OR_NULL(hsotg->phy) && IS_ERR_OR_NULL(hsotg->uphy)) {
>> + plat = dev_get_platdata(dev);
>> + if (!plat) {
>> + dev_err(dev,
>> + "no platform data or transceiver defined\n");
>> + return -EPROBE_DEFER;
>> + }
>> + hsotg->plat = plat;
>> + } else if (hsotg->phy) {
> You have changed the behavior here. Previously, the driver would work
> even if there were no phys or pdata defined. Now it will return
> -EPROBE_DEFER instead. Are you sure that won't break any existing
> platforms?
>
I don't really catch your meaning. Could you please point out where is
the difference? Thanks .

In previous version, if there were no phy or usb_phy defined,
devm_phy_get() and devm_usb_get_phy() both failed, then driver falls
back to find pdata, if no pdata defined dev_get_platdata() returns NULL,
then dwc2_gadget_init returns -EPROBE_DEFER and the dwc2_driver_probe
fail. So I think, for the dwc2 driver without my patch, when
CONFIG_USB_DWC2_PERIPHERAL or CONFIG_USB_DWC2_DUAL_ROLE selected, if
there were no phys or pdata defined, the driver probe will also return
-EPROBE_DEFER. And when only CONFIG_USB_DWC2_HOST selected, the previous
version driver didn't care any thing about phy, in my patch it will try
to find a phy when platform driver probe, but do not fail probe if there
isn't a phy node.




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