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Wed, 05 Aug 2026 12:01:50 -0700 (PDT) Received: from localhost ([2605:1700:2080:8400:6387:b412:85a5:8bb7]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3903d2f9a9fsm2150287a91.1.2026.08.05.12.01.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Aug 2026 12:01:49 -0700 (PDT) Date: Wed, 5 Aug 2026 12:01:47 -0700 From: Bart Nagel To: Michal Pecio Cc: linux-usb@vger.kernel.org, mathias.nyman@intel.com Subject: Re: Regression: webcam freezing since Linux 6.15 Message-ID: Mail-Followup-To: Michal Pecio , linux-usb@vger.kernel.org, mathias.nyman@intel.com References: <20260723081440.0228c59e.michal.pecio@gmail.com> <20260725115956.321185a1.michal.pecio@gmail.com> <20260728003131.085171ee.michal.pecio@gmail.com> <20260730130814.65f7891c.michal.pecio@gmail.com> <20260730235953.2d51e0cc.michal.pecio@gmail.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260730235953.2d51e0cc.michal.pecio@gmail.com> At 2026-07-30 23:59:53 +0200, Michal Pecio wrote: > On Thu, 30 Jul 2026 11:13:59 -0700, Bart Nagel wrote: > > At 2026-07-30 13:08:14 +0200, Michal Pecio wrote: > > > I'm slightly curious what exactly happens there (probably MSE after > > > Short Packet on a single-TRB TD), and whether Missed Service Error > > > may point at a Link TRB, because the current fix wouldn't handle > > > that and the stream could still hang. So your failure rate may > > > actually be reduced to 1/255 of what it was, but still not zero. > > > > > > If possible, please boot the patched kernel again and run it for > > > a little longer. If it fails, post dmesg starting from the "Miss > > > service interval error" line which is followed by "All TDs skipped". > > > > > > And while that is running, also collect another log: > > > > > > cd /sys/kernel/tracing/ > > > echo 1 > events/xhci-hcd/xhci_handle_event/enable > > > echo 1 > tracing_on > > > grep -B5 Missed trace_pipe | tee /tmp/trace > > > > > > This is supposed to log 6 lines for every Missed Service Error, so > > > it will grow, but not terribly fast. > > > > Before I make a bad assumption and collect a useless log, please > > confirm for me exactly which debugging I should enable. Just the two > > you gave above, or also one or both of the ones I was using before: > > > > echo "func handle_tx_event +p" >/proc/dynamic_debug/control > > echo 0xff >/sys/module/uvcvideo/parameters/trace > > Yes, please keep handle_tx_event, otherwise xhci_hcd debug messages > won't show up. UVC trace is not that important. OK. I ran it with your temporary patch for around 24 hours with heavy system load and didn't get any freezes. The logs are large; please let me know if there's anything I can grep for which might tell us that the potential 1/255 chance of a freeze still being possible is ruled out. If you'd like me to run it longer I could, but I otherwise intend now to switch over to your more formal patch. I will post a question in that thread shortly. --bart