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

[Marek Vasut]

On 12/8/23 01:16, Shantur Rathore wrote:
> Hi Marek,
> 
> On Tue, Dec 5, 2023 at 5:40 AM Marek Vasut <marex at denx.de> wrote:
>>
>> On 12/4/23 13:10, Shantur Rathore wrote:
>>> On Mon, Dec 4, 2023 at 11:05 AM Marek Vasut <marex at denx.de> wrote:
>>>>
>>>> On 12/4/23 11:59, Shantur Rathore wrote:
>>>>> 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.
>>>>
>>>> Is there going to be a matching Linux kernel patch with a Linux side fix ?
>>>>
>>>> If so, include a link to that patch in lore.k.o in the commit message,
>>>> and either temporarily fix it up in u-boot.dtsi or backport that patch
>>>> to U-Boot DT, either works.
>>>
>>> So there is no patch in lore.k.o for this and the more I looked the more
>>> dts needed fixing related  usb. I would rather do it in one go and submit
>>> proper patches to lore.k.o and u-boot.
>>>
>>> For now, as usb reset is independent of the rockpro64 regulator issue, can
>>> you please merge this and I will work on dts fixes separately.
>>
>> I'll wait for the regulator fix and them merge them both.
>>
>> This affects too many systems and I'm reluctant to put this into current
>> release at rc4, so there should be plenty of time until the next release.
> 
> Apologies for the late reply.
> 
> I have sent both the patches here
> https://patchwork.ozlabs.org/project/uboot/list/?series=385763

Thanks