Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device controller

[Felipe Balbi]

Hi,

Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes:
> Jun Li wrote:
>>> -----Original Message-----
>>> From: Felipe Balbi <balbif@xxxxxxxxx> On Behalf Of Felipe Balbi
>>> Sent: 2020å5æ15æ 17:31
>>> To: Jun Li <lijun.kernel@xxxxxxxxx>
>>> Cc: John Stultz <john.stultz@xxxxxxxxxx>; lkml <linux-kernel@xxxxxxxxxxxxxxx>; Yu
>>> Chen <chenyu56@xxxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Rob
>>> Herring <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; ShuFan Lee
>>> <shufan_lee@xxxxxxxxxxx>; Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>;
>>> Suzuki K Poulose <suzuki.poulose@xxxxxxx>; Chunfeng Yun
>>> <chunfeng.yun@xxxxxxxxxxxx>; Hans de Goede <hdegoede@xxxxxxxxxx>; Andy Shevchenko
>>> <andy.shevchenko@xxxxxxxxx>; Valentin Schneider <valentin.schneider@xxxxxxx>;
>>> Jack Pham <jackp@xxxxxxxxxxxxxx>; Linux USB List <linux-usb@xxxxxxxxxxxxxxx>; open
>>> list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <devicetree@xxxxxxxxxxxxxxx>;
>>> Peter Chen <peter.chen@xxxxxxx>; Jun Li <jun.li@xxxxxxx>; Thinh Nguyen
>>> <Thinh.Nguyen@xxxxxxxxxxxx>
>>> Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device
>>> controller
>>>
>>>
>>> Hi,
>>>
>>> Jun Li <lijun.kernel@xxxxxxxxx> writes:
>>>>> @@ -397,12 +407,18 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned
>>> cmd,
>>>>>                          dwc3_gadget_ep_get_transfer_index(dep);
>>>>>          }
>>>>>
>>>>> -       if (saved_config) {
>>>>> +       if (saved_hs_config) {
>>>>>                  reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
>>>>> -               reg |= saved_config;
>>>>> +               reg |= saved_hs_config;
>>>>>                  dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
>>>>>          }
>>>>>
>>>>> +       if (saved_ss_config) {
>>>>> +               reg = dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0));
>>>>> +               reg |= saved_ss_config;
>>>>> +               dwc3_writel(dwc->regs, DWC3_GUSB3PIPECTL(0), reg);
>>>>> +       }
>>>>> +
>>>>>          return ret;
>>>>>   }
>>>> Unfortunately this way can't work, once the SS PHY enters P3, disable
>>>> suspend_en can't force SS PHY exit P3, unless do this at the very
>>>> beginning to prevent SS PHY entering P3(e.g. add "snps,dis_u3_susphy_quirk" for
>>> test).
>>>
>>> It sounds like you have a quirky PHY.
>>  From what I got from the IC design, the behavior of DWC3_GUSB3PIPECTL_SUSPHY
>> bit should be as what I said, not a quirky.
>>
>> Hi Thinh, could you comment this?
>
> You only need to wake up the usb2 phy when issuing the command while 
> running in highspeed or below. If you're running in SS or higher, 
> internally the controller does it for you for usb3 phy. In Jun's case, 
> it seems like it takes longer for his phy to wake up.
>
> IMO, in this case, I think it's fine to increase the command timeout.

Is there an upper limit to this? Is 32k clock the slowest that can be
fed to the PHY as a suspend clock?

-- 
balbi

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