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

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Date:   Sat, 16 May 2020 10:12:39 +0300
From:   Felipe Balbi <balbi@...nel.org>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>, Jun Li <jun.li@....com>,
        Jun Li <lijun.kernel@...il.com>
Cc:     John Stultz <john.stultz@...aro.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Yu Chen <chenyu56@...wei.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        ShuFan Lee <shufan_lee@...htek.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Jack Pham <jackp@...eaurora.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        "open list\:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Peter Chen <peter.chen@....com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device controller


Hi,

Thinh Nguyen <Thinh.Nguyen@...opsys.com> writes:
> Jun Li wrote:
>>> -----Original Message-----
>>> From: Felipe Balbi <balbif@...il.com> On Behalf Of Felipe Balbi
>>> Sent: 2020年5月15日 17:31
>>> To: Jun Li <lijun.kernel@...il.com>
>>> Cc: John Stultz <john.stultz@...aro.org>; lkml <linux-kernel@...r.kernel.org>; Yu
>>> Chen <chenyu56@...wei.com>; Greg Kroah-Hartman <gregkh@...uxfoundation.org>; Rob
>>> Herring <robh+dt@...nel.org>; Mark Rutland <mark.rutland@....com>; ShuFan Lee
>>> <shufan_lee@...htek.com>; Heikki Krogerus <heikki.krogerus@...ux.intel.com>;
>>> Suzuki K Poulose <suzuki.poulose@....com>; Chunfeng Yun
>>> <chunfeng.yun@...iatek.com>; Hans de Goede <hdegoede@...hat.com>; Andy Shevchenko
>>> <andy.shevchenko@...il.com>; Valentin Schneider <valentin.schneider@....com>;
>>> Jack Pham <jackp@...eaurora.org>; Linux USB List <linux-usb@...r.kernel.org>; open
>>> list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <devicetree@...r.kernel.org>;
>>> Peter Chen <peter.chen@....com>; Jun Li <jun.li@....com>; Thinh Nguyen
>>> <Thinh.Nguyen@...opsys.com>
>>> Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device
>>> controller
>>>
>>>
>>> Hi,
>>>
>>> Jun Li <lijun.kernel@...il.com> 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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