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

From: Jun Li <jun.li@nxp.com>
To: Felipe Balbi <balbi@kernel.org>,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Jun Li <lijun.kernel@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Yu Chen <chenyu56@huawei.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	ShuFan Lee <shufan_lee@richtek.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Jack Pham <jackp@codeaurora.org>,
	Linux USB List <linux-usb@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>, Peter Chen <peter.chen@nxp.com>
Subject: RE: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device controller
Date: Thu, 21 May 2020 07:47:57 +0000	[thread overview]
Message-ID: <VE1PR04MB6528AC4D33F7F921B65AA1B889B70@VE1PR04MB6528.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <87r1vdx0w4.fsf@kernel.org>

Hi Felipe,

> -----Original Message-----
> From: Felipe Balbi <balbif@gmail.com> On Behalf Of Felipe Balbi
> Sent: 2020年5月21日 14:23
> To: Thinh Nguyen <Thinh.Nguyen@synopsys.com>; Jun Li <jun.li@nxp.com>; Jun Li
> <lijun.kernel@gmail.com>
> Cc: John Stultz <john.stultz@linaro.org>; lkml <linux-kernel@vger.kernel.org>; Yu
> Chen <chenyu56@huawei.com>; Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Rob
> Herring <robh+dt@kernel.org>; Mark Rutland <mark.rutland@arm.com>; ShuFan Lee
> <shufan_lee@richtek.com>; Heikki Krogerus <heikki.krogerus@linux.intel.com>;
> Suzuki K Poulose <suzuki.poulose@arm.com>; Chunfeng Yun
> <chunfeng.yun@mediatek.com>; Hans de Goede <hdegoede@redhat.com>; Andy Shevchenko
> <andy.shevchenko@gmail.com>; Valentin Schneider <valentin.schneider@arm.com>;
> Jack Pham <jackp@codeaurora.org>; Linux USB List <linux-usb@vger.kernel.org>; open
> list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <devicetree@vger.kernel.org>;
> Peter Chen <peter.chen@nxp.com>
> Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device
> controller
> 
> 
> Hi Jun,
> 
> Felipe Balbi <balbi@kernel.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