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

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Date:   Fri, 15 May 2020 13:41:23 +0300
From:   Felipe Balbi <balbi@...nel.org>
To:     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,

Jun Li <jun.li@....com> writes:
>> 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?
>
>> If that's the case, then you probably need
>> to use the flag you mentioned above. Please verify with that.
>
> With quirk of "snps,dis_u3_susphy_quirk", I had verified it can
> resolve the problem, but this will make USB3 Super Speed PHY
> never enter P3, this is a huge impact on USB power consumption.
>
> The timeout increase has no impact on those platforms which have
> no this problem, but can give chance for platform with very low
> supspend clk(like my case 32k) to work.

I was under the impression that issuing a command would wake the PHY
up. I don't have access to DWC3 documentation to verify, but that's as I
remember. Is that not the case?

-- 
balbi

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