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x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfGVUutSsMeCKIM3GkKYTbl3bQnzyrsi2/3nMKqRsUMTt/a3tZBFF/IiCaerxsDYTqFwxfYmQ5yV6bGRS/8LNBl/sfHMn9rKvmvqbIvzMNL+FnbDmqTHz 8PzPbQsKUtFGLTD7fLzOY30q6BogVme3C/85pMwtimpMmLKVH78oZ+HG0DahbuCb/zJr2IEMmW8qnlk7nqk5zpFXlAHoNnMuF82I1MT8Wc/A5szFQplSDRaD X-CM-Analysis: v=2.3 cv=NPP7BXyg c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=kj9zAlcOel0A:10 a=VUJBJC2UJ8kA:10 a=cm27Pg_UAAAA:8 a=VwQbUJbxAAAA:8 a=oIxziwFaEq1Biwc6ZicA:9 a=CjuIK1q_8ugA:10 a=x8gzFH9gYPwA:10 a=xmb-EsYY8bH0VWELuYED:22 a=AjGcO6oz07-iQ99wixmX:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933756AbeEWQkB (ORCPT ); Wed, 23 May 2018 12:40:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:57614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933662AbeEWQjy (ORCPT ); Wed, 23 May 2018 12:39:54 -0400 Date: Wed, 23 May 2018 18:39:37 +0200 From: Greg Kroah-Hartman To: Alan Stern Cc: Nicolas Boichat , linux-usb@vger.kernel.org, Mathias Nyman , Felipe Balbi , Eugene Korenevsky , Peter Chen , Daniel Drake , Joe Perches , Johan Hovold , Richard Leitner , linux-kernel@vger.kernel.org, groeck@chromium.org Subject: Re: [PATCH] usb: hub: Per-port setting to use old enumeration scheme Message-ID: <20180523163936.GE12456@kroah.com> References: <20180523021656.122455-1-drinkcat@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-usb-owner@vger.kernel.org X-Mailing-List: linux-usb@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, May 23, 2018 at 10:03:55AM -0400, Alan Stern wrote: > On Wed, 23 May 2018, Nicolas Boichat wrote: > > > The "old" enumeration scheme is considerably faster (it takes > > ~294ms instead of ~439ms to get the descriptor). > > > > It is currently only possible to use the old scheme globally > > (/sys/module/usbcore/parameters/old_scheme_first), which is not > > desirable as the new scheme was introduced to increase compatibility > > with more devices. > > > > However, in our case, we care about time-to-active for a specific > > USB device (which we make the firmware for), on a specific port > > (that is pogo-pin based: not a standard USB port). This new > > sysfs option makes it possible to use the old scheme on a single > > port only. > > > > Signed-off-by: Nicolas Boichat > > --- > > > > There are other "quirks" that we could add to reduce further > > enumeration time (e.g. reduce USB debounce time, reduce TRSTRCY > > to 10ms instead of 50ms as used currently), but the logic is quite > > similar, so it'd be good to have this reviewed first. > > I'm not opposed to the idea in principle, although I don't like your > implementation because it breaks the original old_scheme_first > parameter. > > Let's see what some other people think. > > Yours is a rather special case, because you know exactly what device > will be attached to a specific port. Still, I can see that sort of > thing happening in constrained and special-purpose settings. > > How do you arrange to set the new quirk before the device is > discovered? Yeah, this last question is what I had when looking at this. Or does it not matter at first boot and only matters for wake-up? thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: usb: hub: Per-port setting to use old enumeration scheme From: Greg Kroah-Hartman Message-Id: <20180523163936.GE12456@kroah.com> Date: Wed, 23 May 2018 18:39:37 +0200 To: Alan Stern Cc: Nicolas Boichat , linux-usb@vger.kernel.org, Mathias Nyman , Felipe Balbi , Eugene Korenevsky , Peter Chen , Daniel Drake , Joe Perches , Johan Hovold , Richard Leitner , linux-kernel@vger.kernel.org, groeck@chromium.org List-ID: T24gV2VkLCBNYXkgMjMsIDIwMTggYXQgMTA6MDM6NTVBTSAtMDQwMCwgQWxhbiBTdGVybiB3cm90 ZToKPiBPbiBXZWQsIDIzIE1heSAyMDE4LCBOaWNvbGFzIEJvaWNoYXQgd3JvdGU6Cj4gCj4gPiBU aGUgIm9sZCIgZW51bWVyYXRpb24gc2NoZW1lIGlzIGNvbnNpZGVyYWJseSBmYXN0ZXIgKGl0IHRh a2VzCj4gPiB+Mjk0bXMgaW5zdGVhZCBvZiB+NDM5bXMgdG8gZ2V0IHRoZSBkZXNjcmlwdG9yKS4K PiA+IAo+ID4gSXQgaXMgY3VycmVudGx5IG9ubHkgcG9zc2libGUgdG8gdXNlIHRoZSBvbGQgc2No ZW1lIGdsb2JhbGx5Cj4gPiAoL3N5cy9tb2R1bGUvdXNiY29yZS9wYXJhbWV0ZXJzL29sZF9zY2hl bWVfZmlyc3QpLCB3aGljaCBpcyBub3QKPiA+IGRlc2lyYWJsZSBhcyB0aGUgbmV3IHNjaGVtZSB3 YXMgaW50cm9kdWNlZCB0byBpbmNyZWFzZSBjb21wYXRpYmlsaXR5Cj4gPiB3aXRoIG1vcmUgZGV2 aWNlcy4KPiA+IAo+ID4gSG93ZXZlciwgaW4gb3VyIGNhc2UsIHdlIGNhcmUgYWJvdXQgdGltZS10 by1hY3RpdmUgZm9yIGEgc3BlY2lmaWMKPiA+IFVTQiBkZXZpY2UgKHdoaWNoIHdlIG1ha2UgdGhl IGZpcm13YXJlIGZvciksIG9uIGEgc3BlY2lmaWMgcG9ydAo+ID4gKHRoYXQgaXMgcG9nby1waW4g YmFzZWQ6IG5vdCBhIHN0YW5kYXJkIFVTQiBwb3J0KS4gVGhpcyBuZXcKPiA+IHN5c2ZzIG9wdGlv biBtYWtlcyBpdCBwb3NzaWJsZSB0byB1c2UgdGhlIG9sZCBzY2hlbWUgb24gYSBzaW5nbGUKPiA+ IHBvcnQgb25seS4KPiA+IAo+ID4gU2lnbmVkLW9mZi1ieTogTmljb2xhcyBCb2ljaGF0IDxkcmlu a2NhdEBjaHJvbWl1bS5vcmc+Cj4gPiAtLS0KPiA+IAo+ID4gVGhlcmUgYXJlIG90aGVyICJxdWly a3MiIHRoYXQgd2UgY291bGQgYWRkIHRvIHJlZHVjZSBmdXJ0aGVyCj4gPiBlbnVtZXJhdGlvbiB0 aW1lIChlLmcuIHJlZHVjZSBVU0IgZGVib3VuY2UgdGltZSwgcmVkdWNlIFRSU1RSQ1kKPiA+IHRv IDEwbXMgaW5zdGVhZCBvZiA1MG1zIGFzIHVzZWQgY3VycmVudGx5KSwgYnV0IHRoZSBsb2dpYyBp cyBxdWl0ZQo+ID4gc2ltaWxhciwgc28gaXQnZCBiZSBnb29kIHRvIGhhdmUgdGhpcyByZXZpZXdl ZCBmaXJzdC4KPiAKPiBJJ20gbm90IG9wcG9zZWQgdG8gdGhlIGlkZWEgaW4gcHJpbmNpcGxlLCBh bHRob3VnaCBJIGRvbid0IGxpa2UgeW91cgo+IGltcGxlbWVudGF0aW9uIGJlY2F1c2UgaXQgYnJl YWtzIHRoZSBvcmlnaW5hbCBvbGRfc2NoZW1lX2ZpcnN0Cj4gcGFyYW1ldGVyLgo+IAo+IExldCdz IHNlZSB3aGF0IHNvbWUgb3RoZXIgcGVvcGxlIHRoaW5rLgo+IAo+IFlvdXJzIGlzIGEgcmF0aGVy IHNwZWNpYWwgY2FzZSwgYmVjYXVzZSB5b3Uga25vdyBleGFjdGx5IHdoYXQgZGV2aWNlCj4gd2ls bCBiZSBhdHRhY2hlZCB0byBhIHNwZWNpZmljIHBvcnQuICBTdGlsbCwgSSBjYW4gc2VlIHRoYXQg c29ydCBvZgo+IHRoaW5nIGhhcHBlbmluZyBpbiBjb25zdHJhaW5lZCBhbmQgc3BlY2lhbC1wdXJw b3NlIHNldHRpbmdzLgo+IAo+IEhvdyBkbyB5b3UgYXJyYW5nZSB0byBzZXQgdGhlIG5ldyBxdWly ayBiZWZvcmUgdGhlIGRldmljZSBpcyAKPiBkaXNjb3ZlcmVkPwoKWWVhaCwgdGhpcyBsYXN0IHF1 ZXN0aW9uIGlzIHdoYXQgSSBoYWQgd2hlbiBsb29raW5nIGF0IHRoaXMuICBPciBkb2VzIGl0Cm5v dCBtYXR0ZXIgYXQgZmlyc3QgYm9vdCBhbmQgb25seSBtYXR0ZXJzIGZvciB3YWtlLXVwPwoKdGhh bmtzLAoKZ3JlZyBrLWgKLS0tClRvIHVuc3Vic2NyaWJlIGZyb20gdGhpcyBsaXN0OiBzZW5kIHRo ZSBsaW5lICJ1bnN1YnNjcmliZSBsaW51eC11c2IiIGluCnRoZSBib2R5IG9mIGEgbWVzc2FnZSB0 byBtYWpvcmRvbW9Admdlci5rZXJuZWwub3JnCk1vcmUgbWFqb3Jkb21vIGluZm8gYXQgIGh0dHA6 Ly92Z2VyLmtlcm5lbC5vcmcvbWFqb3Jkb21vLWluZm8uaHRtbAo=