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: <20180525062913.GA11968@kroah.com> Date: Fri, 25 May 2018 08:29:13 +0200 To: Nicolas Boichat Cc: Alan Stern , linux-usb@vger.kernel.org, Mathias Nyman , Felipe Balbi , Eugene Korenevsky , Peter Chen , Daniel Drake , Joe Perches , Johan Hovold , Richard Leitner , lkml , Guenter Roeck List-ID: T24gRnJpLCBNYXkgMjUsIDIwMTggYXQgMDY6MDU6MTZBTSArMDgwMCwgTmljb2xhcyBCb2ljaGF0 IHdyb3RlOgo+IE9uIEZyaSwgTWF5IDI1LCAyMDE4IGF0IDEyOjIxIEFNLCBHcmVnIEtyb2FoLUhh cnRtYW4KPiA8Z3JlZ2toQGxpbnV4Zm91bmRhdGlvbi5vcmc+IHdyb3RlOgo+ID4gT24gVGh1LCBN YXkgMjQsIDIwMTggYXQgMDc6NDI6MDBBTSArMDgwMCwgTmljb2xhcyBCb2ljaGF0IHdyb3RlOgo+ ID4+IE9uIFRodSwgTWF5IDI0LCAyMDE4IGF0IDEyOjM5IEFNLCBHcmVnIEtyb2FoLUhhcnRtYW4K PiA+PiA8Z3JlZ2toQGxpbnV4Zm91bmRhdGlvbi5vcmc+IHdyb3RlOgo+ID4+ID4gT24gV2VkLCBN YXkgMjMsIDIwMTggYXQgMTA6MDM6NTVBTSAtMDQwMCwgQWxhbiBTdGVybiB3cm90ZToKPiA+PiA+ PiBPbiBXZWQsIDIzIE1heSAyMDE4LCBOaWNvbGFzIEJvaWNoYXQgd3JvdGU6Cj4gPj4gPj4KPiA+ PiA+PiA+IFRoZSAib2xkIiBlbnVtZXJhdGlvbiBzY2hlbWUgaXMgY29uc2lkZXJhYmx5IGZhc3Rl ciAoaXQgdGFrZXMKPiA+PiA+PiA+IH4yOTRtcyBpbnN0ZWFkIG9mIH40MzltcyB0byBnZXQgdGhl IGRlc2NyaXB0b3IpLgo+ID4+ID4+ID4KPiA+PiA+PiA+IEl0IGlzIGN1cnJlbnRseSBvbmx5IHBv c3NpYmxlIHRvIHVzZSB0aGUgb2xkIHNjaGVtZSBnbG9iYWxseQo+ID4+ID4+ID4gKC9zeXMvbW9k dWxlL3VzYmNvcmUvcGFyYW1ldGVycy9vbGRfc2NoZW1lX2ZpcnN0KSwgd2hpY2ggaXMgbm90Cj4g Pj4gPj4gPiBkZXNpcmFibGUgYXMgdGhlIG5ldyBzY2hlbWUgd2FzIGludHJvZHVjZWQgdG8gaW5j cmVhc2UgY29tcGF0aWJpbGl0eQo+ID4+ID4+ID4gd2l0aCBtb3JlIGRldmljZXMuCj4gPj4gPj4g Pgo+ID4+ID4+ID4gSG93ZXZlciwgaW4gb3VyIGNhc2UsIHdlIGNhcmUgYWJvdXQgdGltZS10by1h Y3RpdmUgZm9yIGEgc3BlY2lmaWMKPiA+PiA+PiA+IFVTQiBkZXZpY2UgKHdoaWNoIHdlIG1ha2Ug dGhlIGZpcm13YXJlIGZvciksIG9uIGEgc3BlY2lmaWMgcG9ydAo+ID4+ID4+ID4gKHRoYXQgaXMg cG9nby1waW4gYmFzZWQ6IG5vdCBhIHN0YW5kYXJkIFVTQiBwb3J0KS4gVGhpcyBuZXcKPiA+PiA+ PiA+IHN5c2ZzIG9wdGlvbiBtYWtlcyBpdCBwb3NzaWJsZSB0byB1c2UgdGhlIG9sZCBzY2hlbWUg b24gYSBzaW5nbGUKPiA+PiA+PiA+IHBvcnQgb25seS4KPiA+PiA+PiA+Cj4gPj4gPj4gPiBTaWdu ZWQtb2ZmLWJ5OiBOaWNvbGFzIEJvaWNoYXQgPGRyaW5rY2F0QGNocm9taXVtLm9yZz4KPiA+PiA+ PiA+IC0tLQo+ID4+ID4+ID4KPiA+PiA+PiA+IFRoZXJlIGFyZSBvdGhlciAicXVpcmtzIiB0aGF0 IHdlIGNvdWxkIGFkZCB0byByZWR1Y2UgZnVydGhlcgo+ID4+ID4+ID4gZW51bWVyYXRpb24gdGlt ZSAoZS5nLiByZWR1Y2UgVVNCIGRlYm91bmNlIHRpbWUsIHJlZHVjZSBUUlNUUkNZCj4gPj4gPj4g PiB0byAxMG1zIGluc3RlYWQgb2YgNTBtcyBhcyB1c2VkIGN1cnJlbnRseSksIGJ1dCB0aGUgbG9n aWMgaXMgcXVpdGUKPiA+PiA+PiA+IHNpbWlsYXIsIHNvIGl0J2QgYmUgZ29vZCB0byBoYXZlIHRo aXMgcmV2aWV3ZWQgZmlyc3QuCj4gPj4gPj4KPiA+PiA+PiBJJ20gbm90IG9wcG9zZWQgdG8gdGhl IGlkZWEgaW4gcHJpbmNpcGxlLCBhbHRob3VnaCBJIGRvbid0IGxpa2UgeW91cgo+ID4+ID4+IGlt cGxlbWVudGF0aW9uIGJlY2F1c2UgaXQgYnJlYWtzIHRoZSBvcmlnaW5hbCBvbGRfc2NoZW1lX2Zp cnN0Cj4gPj4gPj4gcGFyYW1ldGVyLgo+ID4+Cj4gPj4gSSBkb24ndCB0aGluayBpdCBicmVha3Mg dGhlIG9yaWdpbmFsIHBhcmFtZXRlcj8gSSBtZWFuLAo+ID4+IC9zeXMvbW9kdWxlL3VzYmNvcmUv cGFyYW1ldGVycy9vbGRfc2NoZW1lX2ZpcnN0IGlzIHN0aWxsIGEgZ2xvYmFsCj4gPj4gZGVmYXVs dCwgd2hpbGUgYml0IDAgb2YgL3N5cy9idXMvdXNiL2RldmljZXMveC95L3ovcXVpcmtzIGJlY29t ZXMgYQo+ID4+IHBvcnQtc3BlY2lmaWMgb3ZlcnJpZGUuCj4gPj4KPiA+PiA+PiBMZXQncyBzZWUg d2hhdCBzb21lIG90aGVyIHBlb3BsZSB0aGluay4KPiA+PiA+Pgo+ID4+ID4+IFlvdXJzIGlzIGEg cmF0aGVyIHNwZWNpYWwgY2FzZSwgYmVjYXVzZSB5b3Uga25vdyBleGFjdGx5IHdoYXQgZGV2aWNl Cj4gPj4gPj4gd2lsbCBiZSBhdHRhY2hlZCB0byBhIHNwZWNpZmljIHBvcnQuICBTdGlsbCwgSSBj YW4gc2VlIHRoYXQgc29ydCBvZgo+ID4+ID4+IHRoaW5nIGhhcHBlbmluZyBpbiBjb25zdHJhaW5l ZCBhbmQgc3BlY2lhbC1wdXJwb3NlIHNldHRpbmdzLgo+ID4+ID4+Cj4gPj4gPj4gSG93IGRvIHlv dSBhcnJhbmdlIHRvIHNldCB0aGUgbmV3IHF1aXJrIGJlZm9yZSB0aGUgZGV2aWNlIGlzCj4gPj4g Pj4gZGlzY292ZXJlZD8KPiA+PiA+Cj4gPj4gPiBZZWFoLCB0aGlzIGxhc3QgcXVlc3Rpb24gaXMg d2hhdCBJIGhhZCB3aGVuIGxvb2tpbmcgYXQgdGhpcy4gIE9yIGRvZXMgaXQKPiA+PiA+IG5vdCBt YXR0ZXIgYXQgZmlyc3QgYm9vdCBhbmQgb25seSBtYXR0ZXJzIGZvciB3YWtlLXVwPwo+ID4+Cj4g Pj4gSXQgZG9lcyBub3QgbWF0dGVyIG9uIGJvb3QsIHdlIGhhdmUgcGxlbnR5IG9mIHRpbWUgdG8g ZW51bWVyYXRlIHRoZQo+ID4+IGRldmljZS4gV2UgdXNlIFVTQiAoYXV0by0pc3VzcGVuZCBhbmQg cmVtb3RlIHdha2UsIHNvIG5vCj4gPj4gcmUtZW51bWVyYXRpb24gdGhlcmUgZWl0aGVyLiBJdCBv bmx5IG1hdHRlcnMgb24gdW5wbHVnL3JlcGx1ZyB3aGVyZQo+ID4+IHRoZSBkZXZpY2UgbmVlZHMg dG8gYmUgcmUtZW51bWVyYXRlZC4KPiA+Cj4gPiBIb3cgZG9lcyB0aGlzIGRldmljZSBnZXQgdW5w bHVnZ2VkL3JlcGx1Z2dlZCBpZiBpdCBpcyBjb25uZWN0ZWQgZGlyZWN0bHkKPiA+IHRvIHRoZSBk ZXZpY2U/Cj4gCj4gSXQgaXMgZXh0ZXJuYWwuIEVzc2VudGlhbGx5LCB0aGlzIGlzIGEgdGFibGV0 IHdpdGggYSBkZXRhY2hhYmxlCj4ga2V5Ym9hcmQvdG91Y2hwYWQuIFRoZSBpbnRlcmZhY2UgYmV0 d2VlbiB0YWJsZXQgYW5kIGJhc2UgaXMgVVNCLCBvdmVyCj4gcG9nbyBwaW5zLiBUaGUgcG9ydCBp cyBub24tc3RhbmRhcmQgKHBvZ28sIG5vdCBub3JtYWwgVVNCKSwgYW5kIHdlCj4gZnVsbHkgY29u dHJvbCB0aGUgZmlybXdhcmUgb24gdGhlIGJhc2Ugc2lkZSBhcyB3ZWxsLCB3aGljaCBhbGxvd3Mg dXMKPiB0byB0YWtlIHNob3J0Y3V0cyBsaWtlIHRoaXM6IHdlIGtub3cgZXhhY3RseSB3aGF0IGRl dmljZSB3aWxsIGJlCj4gY29ubmVjdGVkIG9uIHRoYXQgcG9ydC4KCkFoLCBvaywgdGhhdCBtYWtl cyBtb3JlIHNlbnNlLCB0aGFua3MgZm9yIHRoZSBleHBsYW5hdGlvbi4gIEknbGwgZ28KcXVldWUg dGhpcyB1cCBpbiBhIGJpdC4KCmdyZWcgay1oCi0tLQpUbyB1bnN1YnNjcmliZSBmcm9tIHRoaXMg bGlzdDogc2VuZCB0aGUgbGluZSAidW5zdWJzY3JpYmUgbGludXgtdXNiIiBpbgp0aGUgYm9keSBv ZiBhIG1lc3NhZ2UgdG8gbWFqb3Jkb21vQHZnZXIua2VybmVsLm9yZwpNb3JlIG1ham9yZG9tbyBp bmZvIGF0ICBodHRwOi8vdmdlci5rZXJuZWwub3JnL21ham9yZG9tby1pbmZvLmh0bWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935836AbeEYG3d (ORCPT ); Fri, 25 May 2018 02:29:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:46808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935695AbeEYG3b (ORCPT ); Fri, 25 May 2018 02:29:31 -0400 Date: Fri, 25 May 2018 08:29:13 +0200 From: Greg Kroah-Hartman To: Nicolas Boichat Cc: Alan Stern , linux-usb@vger.kernel.org, Mathias Nyman , Felipe Balbi , Eugene Korenevsky , Peter Chen , Daniel Drake , Joe Perches , Johan Hovold , Richard Leitner , lkml , Guenter Roeck Subject: Re: [PATCH] usb: hub: Per-port setting to use old enumeration scheme Message-ID: <20180525062913.GA11968@kroah.com> References: <20180523021656.122455-1-drinkcat@chromium.org> <20180523163936.GE12456@kroah.com> <20180524162157.GA26662@kroah.com> 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-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 25, 2018 at 06:05:16AM +0800, Nicolas Boichat wrote: > On Fri, May 25, 2018 at 12:21 AM, Greg Kroah-Hartman > wrote: > > On Thu, May 24, 2018 at 07:42:00AM +0800, Nicolas Boichat wrote: > >> On Thu, May 24, 2018 at 12:39 AM, Greg Kroah-Hartman > >> wrote: > >> > 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. > >> > >> I don't think it breaks the original parameter? I mean, > >> /sys/module/usbcore/parameters/old_scheme_first is still a global > >> default, while bit 0 of /sys/bus/usb/devices/x/y/z/quirks becomes a > >> port-specific override. > >> > >> >> 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? > >> > >> It does not matter on boot, we have plenty of time to enumerate the > >> device. We use USB (auto-)suspend and remote wake, so no > >> re-enumeration there either. It only matters on unplug/replug where > >> the device needs to be re-enumerated. > > > > How does this device get unplugged/replugged if it is connected directly > > to the device? > > It is external. Essentially, this is a tablet with a detachable > keyboard/touchpad. The interface between tablet and base is USB, over > pogo pins. The port is non-standard (pogo, not normal USB), and we > fully control the firmware on the base side as well, which allows us > to take shortcuts like this: we know exactly what device will be > connected on that port. Ah, ok, that makes more sense, thanks for the explanation. I'll go queue this up in a bit. greg k-h