From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 623ABC433DB for ; Fri, 22 Jan 2021 13:28:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 32DCF23437 for ; Fri, 22 Jan 2021 13:28:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727933AbhAVN2J (ORCPT ); Fri, 22 Jan 2021 08:28:09 -0500 Received: from mx4.wp.pl ([212.77.101.12]:19475 "EHLO mx4.wp.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727844AbhAVN1s (ORCPT ); Fri, 22 Jan 2021 08:27:48 -0500 Received: (wp-smtpd smtp.wp.pl 7307 invoked from network); 22 Jan 2021 14:26:50 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wp.pl; s=1024a; t=1611322011; bh=yA9yVqrJ3gaZW+uOgUd/gxZpdCsHjZBcVXElQwFmBG0=; h=From:To:Cc:Subject; b=c1aP54HkMnCS9qGrAorIcjYZUBD/m9+CJfieHAss5ulDN7KnW/I9TFize1+D7rkqR Rf/+eCVm9TvO2MZmOT0PCnYBBBIjr7kVnGdkn/ST0abOqP+OAZujZyQWujvpdZWwKr Kz9dvOQuUsOzZWiIwnHu+rN9WXU/JQmkRvvaaY88= Received: from ip4-46-39-164-203.cust.nbox.cz (HELO localhost) (stf_xl@wp.pl@[46.39.164.203]) (envelope-sender ) by smtp.wp.pl (WP-SMTPD) with ECDHE-RSA-AES256-GCM-SHA384 encrypted SMTP for ; 22 Jan 2021 14:26:50 +0100 Date: Fri, 22 Jan 2021 14:26:50 +0100 From: Stanislaw Gruszka To: Greg KH Cc: linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, Mathias Nyman , Bernhard Subject: Re: [PATCH] usb, xhci, rt2800usb: do not perform Soft Retry Message-ID: <20210122132650.GA13029@wp.pl> References: <20210122104342.12451-1-stf_xl@wp.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-WP-MailID: 9f445cc3152969504b5d2e7df78eb0bf X-WP-AV: skaner antywirusowy Poczty Wirtualnej Polski X-WP-SPAM: NO 0000000 [kePk] Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Fri, Jan 22, 2021 at 12:56:30PM +0100, Greg KH wrote: > On Fri, Jan 22, 2021 at 11:43:42AM +0100, stf_xl@wp.pl wrote: > > From: Stanislaw Gruszka > > > > Since f8f80be501aa ("xhci: Use soft retry to recover faster from transaction > > errors") on some systems rt2800usb devices are unable to operate. Looks > > that due to firmware or hardware limitations of those devices, they > > require full recovery from USB Transaction Errors. > > > > To avoid the problem add URB transfer flag, that restore pre f8f80be501aa > > xhci behaviour when the flag is set. For now only add it only to rt2800usb > > driver. > > This feels like a really heavy hammer, to add a xhci flag for a single > broken device. > > Are you sure this is really needed? I'm not sure if this is needed, however this particular bug was reported as regression caused by f8f80be501aa commit on 4.19 -> 4.20 cycle. It was reported to Mathias Nyman - xhci maintainer and f8f80be501aa commit author. But since then, regardless of some Mathias work on this on xhci side, we did not get solution that fixed the problem. >From other side, I can ask why change from f8f80be501aa is need? Taking it's commit message, the benefit of the change is not obvious. What I can notice, is that it only broke support for hardware that worked previously. However I assume that the change is useful and needed, so I come up with patch that just revert this change only for rt2800usb. > What does this device do on other > operating systems, do they have such a quirk for their host controller > driver? I don't know what other OSes do. > Or is this due to the specific host controller device hardware? Should > this be a xhci quirk for a specific pci device instead? That certainly possible. However taking that the issue is observed only when usb bus transition error happens, what I think can be very rare, it's not easy to identify actual culprit of the problem. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202541 > > Fixes: f8f80be501aa ("xhci: Use soft retry to recover faster from transaction errors") > > Reported-and-tested-by: Bernhard > > Bisected-by: Bernhard > > Signed-off-by: Stanislaw Gruszka > > --- > > drivers/net/wireless/ralink/rt2x00/rt2x00usb.c | 3 +++ > > drivers/usb/core/urb.c | 2 +- > > drivers/usb/host/xhci-ring.c | 3 ++- > > include/linux/usb.h | 1 + > > 4 files changed, 7 insertions(+), 2 deletions(-) [snip] > > --- a/include/linux/usb.h > > +++ b/include/linux/usb.h > > @@ -1329,6 +1329,7 @@ extern int usb_disabled(void); > > #define URB_ISO_ASAP 0x0002 /* iso-only; use the first unexpired > > * slot in the schedule */ > > #define URB_NO_TRANSFER_DMA_MAP 0x0004 /* urb->transfer_dma valid on submit */ > > +#define URB_SOFT_RETRY_NOT_OK 0x0008 /* Avoid XHCI Soft Retry */ > > To match other flags here, how about "URB_NO_SOFT_RETRY"? I named the flag based on existing "URB_SHORT_NOT_OK" flag, but I could rename it to URB_NO_SOFT_RETRY, no problem with that. Stanislaw