[PATCH] common: usb-hub: Reset hub port before scanning

[Shantur Rathore]

Hi Marek,

On Sun, Dec 3, 2023 at 10:37 PM Marek Vasut <marex at denx.de> wrote:
>
> On 12/3/23 22:42, Shantur Rathore wrote:
> > Hi Marek,
> >
> > On Sun, Dec 3, 2023 at 8:42 PM Marek Vasut <marex at denx.de> wrote:
> >>
> >> On 11/24/23 01:37, Shantur Rathore wrote:
> >>> Hi Marek,
> >>
> >> Hi,
> >>
> >> sorry for the late reply.
> >>
> >>>>>>> In my case RockPro64, the power to usb ports onboard is controlled by
> >>>>>>> a regulator.
> >>>>>>> This regulator is enabled as part of init  as here
> >>>>>>> https://github.com/u-boot/u-boot/blob/master/arch/arm/dts/rk3399-rockpro64.dtsi#L177
> >>>>>>>
> >>>>>>> On init, the usb devices connected to the port are powered up, in my
> >>>>>>> case AM8180 (a RTL9210 based ) NVMe to USB enclosure with UAS.
> >>>>>>> But the usb controller is only enabled at 'usb start' and by this time
> >>>>>>> the device is in some state that it doesn't get detected.
> >>>>>>>
> >>>>>>> One way to make sure the devices connected to the ports are in an
> >>>>>>> initialising state is by issuing a port reset before scanning the
> >>>>>>> port.
> >>>>>>
> >>>>>> Why not remove this regulator-always-on and let the PHY driver turn the
> >>>>>> VBUS ON only when it is needed ?
> >>>>>>
> >>>>>> Wouldn't that solve the problem too AND remove unnecessarily enabled
> >>>>>> regulator ?
> >>>>>>
> >>>>>> [...]
> >>>>>
> >>>>> Removing the regulator-always-on does make it work but there are few issues
> >>>>>
> >>>>> 1. regulator is used to control power to multiple ports ( USB3.0 and
> >>>>> USB2.0 in RockPro64 ),
> >>>>> so this could lead to all ports turning off if a phy resets / turns off power
> >>>>
> >>>> I vaguely recall seeing some refcounting patch for regulator subsystem,
> >>>> would that help ?
> >>>
> >>> I don't think this would be a problem for u-boot, but linux maybe.
> >>
> >> How so ?
> >
> > Actually, I am wrong. I wasn't sure if there is refcounting for the
> > regulator subsystem
> > in linux. just found it has so this is null and void.
> >
> >>
> >>>>> 2. Even with regulator-always-on and without this reset port patch,
> >>>>> linux was always
> >>>>> able to detect the drive on the port, so there is something missing in u-boot.
> >>>>> 3. Looking at usb hub code in Linux, I found that for USB3.0 it tries
> >>>>> to reset the port before
> >>>>> scanning. The comment says
> >>>>>
> >>>>> /* Is a USB 3.0 port in the Inactive or Compliance Mode state?
> >>>>>     * Port warm reset is required to recover
> >>>>>     */
> >>>>>
> >>>>> i. https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L5736
> >>>>> ii. https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L2836
> >>>>>
> >>>>> I believe this isn't implemented in u-boot and hence explicit reset of
> >>>>> a port fixes the issue.
> >>>>
> >>>> I feel this is separate issue and what needs to be fixed first is the
> >>>> hard-wired VBus control.
> >>>
> >>> I beg to differ on this, couple of reasons for this
> >>>
> >>> 1. The same drive works fine without being reset on the USB2.0 ports - this
> >>> confirms that the issue is related to USB3.0 only.
> >>
> >> This is a separate issue from the hard-wired VBus control. I agree the
> >> issue does exist, I would simply like to avoid conflating the hard-wired
> >> VBus control with device reset.
> >>
> >>> 2. Linux is able to detect the same drive on USB3.0 when u-boot fails - this
> >>> confirms issue doesn't lie with regulator-always-on
> >>
> >> See above
> >>
> >>> 3. The links I pasted earlier mentions that in USB3.0 the ports need reset
> >>> and this is done before the port is scanned. Adding the similar reset in u-boot
> >>> fixes all with the same regulator-always-on. AFAIK u-boot doesn't handle
> >>> this special USB3.0 case and maybe this is why I was finding a few posts
> >>> around the drive not being detected in the USB3.0 port in u-boot but works in
> >>> a USB2.0 port.
> >>
> >> I am not disputing the need for USB 3.0 device reset, I believe there
> >> are two issues here -- one is the hard-wired VBus regulator -- the other
> >> is this USB 3.0 reset. They should both be fixed.
> >
> > Sure, agreed 100%.
> > Do we need to fix both at the same time?
> > Both patches seem to be independent.
>
> Separate patch for the regulator please .

Thanks, I am working on the regulator patch for rk3399-rockpro64-u-boot but
there seems to be a bug in the rk3399-rockpro64.dtsi from linux where
the typec phy
is configure with wrong regulator and if I do the patch as below

--- a/arch/arm/dts/rk3399-rockpro64-u-boot.dtsi
+++ b/arch/arm/dts/rk3399-rockpro64-u-boot.dtsi
@@ -22,6 +22,23 @@
        };
 };

+&vcc5v0_host {
+       /delete-property/ regulator-always-on;
+};
+
+&vcc5v0_typec {
+       /delete-property/ regulator-always-on;
+};
+
+&vcc5v0_usb {
+       /delete-property/ regulator-always-on;
+       /delete-property/ regulator-boot-on;
+};

The typec port won't work until I correct the issue with

+&u2phy1_host {
+       phy-supply = <&vcc5v0_typec>;
+};
+

What would be acceptable here?
1. Leave regulator for typec as it was
2. disable regulator-always-on and fix phy here.

Kind regards,
Shantur