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

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Message-ID: <VE1PR04MB6528AC4D33F7F921B65AA1B889B70@VE1PR04MB6528.eurprd04.prod.outlook.com>
Date:   Thu, 21 May 2020 07:47:57 +0000
From:   Jun Li <jun.li@....com>
To:     Felipe Balbi <balbi@...nel.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.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>
Subject: RE: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by
 device controller

Hi Felipe,

> -----Original Message-----
> From: Felipe Balbi <balbif@...il.com> On Behalf Of Felipe Balbi
> Sent: 2020年5月21日 14:23
> 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>
> Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device
> controller
> 
> 
> Hi Jun,
> 
> Felipe Balbi <balbi@...nel.org> writes:
> >> In any case, increasing the timeout should be fine with me. It maybe
> >> difficult to determine the max timeout base on the slowest clock rate
> >> and number of cycles. Different controller and controller versions
> >> behave differently and may have different number of clock cycles to
> >> complete a command.
> >>
> >> The RTL engineer recommended timeout to be at least 1ms (which maybe
> >> more than the polling rate of this patch). I'm fine with either the
> >> rate provided by this tested patch or higher.
> >
> > A whole ms waiting for a command to complete? Wow, that's a lot of
> > time blocking the CPU. It looks like, perhaps, we should move to
> > command completion interrupts. The difficulty here is that we issue
> > commands from within the interrupt handler and, as such, can't
> > wait_for_completion().
> >
> > Meanwhile, we will take the timeout increase I guess, otherwise NXP
> > won't have a working setup.
> 
> patch 1 in this series doesn't apply to testing/next. Care to rebase and resend?

Sure, I will rebase and resend this patch with timeout loop 5000.

Thanks
Li Jun
> 
> Thank you
> 
> --
> balbi