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

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Message-ID: <VE1PR04MB65283F16826D2254128073C589BD0@VE1PR04MB6528.eurprd04.prod.outlook.com>
Date:   Fri, 15 May 2020 10:07:25 +0000
From:   Jun Li <jun.li@....com>
To:     Felipe Balbi <balbi@...nel.org>, 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



> -----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?

> 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.

Thanks
Li Jun
> 
> --
> balbi