Hi Jules,
On 12/16/2020 20:59, Jules Maselbas wrote:
> On probe the dwc2 driver tries two path to get an usb phy, first calling
> devm_phy_get() and secondly with devm_usb_get_phy().
>
> However the current implementation of devm_phy_get() never return a valid
> phy for usb-nop-xceiv. And the current implementation of devm_usb_get_phy
> only check for phy that's has already been registered.
>
> During boot, I see the dwc2 driver being probed before the usb-nop-xceiv
> probe, this means that during the dwc2 probe the function devm_usb_get_phy
> never finds the a phy (because it hasn't been registered yet) but never
> cause the dwc2 probe to defer.
>
> I tried to follow what is done by dwc3_core_get_phy(): if the current
> device has an of_node then try to get the usb_phy by phandle instead of
> using devm_usb_get_phy(). This way when the probe order is not good the
> devm_usb_get_phy_by_phandle() function will return -EPROBE_DEFER.
>
> Signed-off-by: Jules Maselbas <jmaselbas@xxxxxxxxx>
> --- 8< ---
>
> A snippet of the device-tree source I am using:
> &usb0 {
> phys = <&usb_phy0>;
> phy-names = "usb2-phy";
> };
> &usb_phy0 {
> #phy-cells = <0>;
> compatible = "usb-nop-xceiv";
> reset-gpios = <&gpio 0 GPIO_ACTIVE_LOW>;
> };
> ---
> drivers/usb/dwc2/platform.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
> index db9fd4bd1a38..b58ce996add7 100644
> --- a/drivers/usb/dwc2/platform.c
> +++ b/drivers/usb/dwc2/platform.c
> @@ -251,7 +251,12 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
> }
>
> if (!hsotg->phy) {
> - hsotg->uphy = devm_usb_get_phy(hsotg->dev, USB_PHY_TYPE_USB2);
> + if (hsotg->dev->of_node)
> + i = of_property_match_string(hsotg->dev->of_node, "phy-names", "usb2-phy");
According the device tree you have provided the value of "i" will always
be "0".
> + if (hsotg->dev->of_node && i >= 0)
> + hsotg->uphy = devm_usb_get_phy_by_phandle(hsotg->dev, "phys", i);
Why do you use the value of "i" while in "<&usb_phy0>" you have only one
phy. If you had several phy-names and the value of "i" gets more than 0,
then based on your usb_phy0 "devm_usb_get_phy_by_phandle" function will
return error. So, maybe it would be more correct (based on your device
tree), to use below command
hsotg->uphy = devm_usb_get_phy_by_phandle(hsotg->dev, "phys", 0);
> + else
> + hsotg->uphy = devm_usb_get_phy(hsotg->dev, USB_PHY_TYPE_USB2);
> if (IS_ERR(hsotg->uphy)) {
> ret = PTR_ERR(hsotg->uphy);
> switch (ret) {
>
Regards,
Artur
