Re: [PATCH 1/3] doc: dt: bindings: usb: dwc3: Update entries for disabling SS instances in park mode

From: Jun Li <lijun.kernel@gmail.com>
To: Tim <elatllat@gmail.com>
Cc: Felipe Balbi <balbi@kernel.org>,
	Jianxin Pan <jianxin.pan@amlogic.com>,
	devicetree@vger.kernel.org, khilman@baylibre.com,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Neil Armstrong <narmstrong@baylibre.com>,
	Dongjin Kim <tobetter@gmail.com>,
	linux-amlogic@lists.infradead.org, Rob Herring <robh@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] doc: dt: bindings: usb: dwc3: Update entries for disabling SS instances in park mode
Date: Tue, 12 Nov 2019 09:48:22 +0800	[thread overview]
Message-ID: <CAKgpwJWj9nqF-j2e+hNZZUtqGY92-2o1cUNWWh0ugePrwjbtsA@mail.gmail.com> (raw)
In-Reply-To: <CA+3zgmtJqN-3Q-kjMhh58B+T7z_1TA-C6be7+UP6nuQb7eq=8A@mail.gmail.com>

by a quirk, those platforms without this quirk can't benefit this fix.

if later this bug is fixed by some reversion of dwc3 IP, we can easily
remove the workaround by a IP version check:
if (dwc->revision < DWC3_REVISION_PARK_MODE_FIXED)
{
          disable park mode for ss;
}

Li Jun

Tim <elatllat@gmail.com> 于2019年11月11日周一 下午10:05写道：
>
> Speculation;
>
> Maybe the kernel maintainers prefer to optimistically permit future
> products to easily remove workarounds via quirk flags.
> Even if data from testing were shown, and it did not impact
> performance, code reduction and clarity are desirable.
>
> On Sun, Nov 10, 2019 at 8:58 PM Jun Li <lijun.kernel@gmail.com> wrote:
> >
> > Hi Neil
> >
> > As I got the information from Synopsys, this bug exists on current IP versions,
> > and per my tests with external USB3 hub + 2 Super speed udisks on data
> > read by dd, I can reproduce this issue with different kernel versions, also I
> > didn't see obvious performance drop by dd tests after disable park mode for
> > super speed, so should we just disable it by default so no need a quirk?
> >
> > Li Jun
> >
> > Tim <elatllat@gmail.com> 于2019年11月11日周一 上午8:42写道：
> > >
> > > Thanks for working on this Neil,
> > > Is there something that needs doing for this patch to make it into 5.3 or 5.4?
> > > As previously mentioned the patch set fixes the issue on affected hardware;
> > >     https://patchwork.kernel.org/patch/11164515/
> > >
> > >
> > >
> > > On Wed, Oct 23, 2019 at 4:11 PM Rob Herring <robh@kernel.org> wrote:
> > > >
> > > > On Mon, Oct 14, 2019 at 04:17:16PM +0200, Neil Armstrong wrote:
> > > > > This patch updates the documentation with the information related
> > > > > to the quirks that needs to be added for disabling all SuperSpeed XHCi
> > > > > instances in park mode.
> > > > >
> > > > > CC: Dongjin Kim <tobetter@gmail.com>
> > > > > Cc: Jianxin Pan <jianxin.pan@amlogic.com>
> > > > > Reported-by: Tim <elatllat@gmail.com>
> > > > > Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> > > > > ---
> > > > >  Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
> > > > >  1 file changed, 2 insertions(+)
> > > >
> > > > Sigh, what's one more to the never ending list of quirks...
> > > >
> > > > Acked-by: Rob Herring <robh@kernel.org>

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