From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8153B84D02 for ; Mon, 8 Sep 2025 23:01:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757372464; cv=none; b=WsmQFonFuP24yowRi8XMC5ZucQIrNF7t5uZ+1Vs8MiD4xKDWt92v6r5lY1JQ+8G7QinRmWBx5u9k/766v6R2eO1waZK367KpL+4B+D3+0z9Er4pVfdguovKmKyhbqar6Q1kGbsDx/uzhAgFRIgpG5v4heB3+RPc7tJ2WPoAwiIQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757372464; c=relaxed/simple; bh=gu7/7QnqcpovYog0TGFKJ8RqmZBkEgfwQD5FguXzHSs=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=cunBTIfN2nrBWbU0w4/2KwgLMVBqaapfUFzDTiGu8T8dw5xfbQLjESZwY6m5dT1hT37MoYbbcg4wsMN4QukYXK1K/+9Sc2RaQ1MmuWkEHmVVaNHNgvfc/sRqTo4AFLKqtH2+RNdqGBsK1mqPvvpBYnw6LvEELS+jkt7pdY1+8Vw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=o/dTgfLR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="o/dTgfLR" Received: by smtp.kernel.org (Postfix) with ESMTPS id 4D4E9C4CEF1 for ; Mon, 8 Sep 2025 23:01:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757372464; bh=gu7/7QnqcpovYog0TGFKJ8RqmZBkEgfwQD5FguXzHSs=; h=From:To:Subject:Date:In-Reply-To:References:From; b=o/dTgfLRLpBfZAtvRtoEADgjDVcavgWjhHcFGogzOXiz0S4MUYWZMU2/RXfrw02n4 6Azt7vvvMDHFNaa5Ac6f+AaOPvt2/yGO+K5GjfIjXG9a7fUddp4y99/8DX5Ki6Aw9N ENrLg1Ra2Ld0WHGjdWB3YuhgHCeNaOQ1iR9G2REZMOCJIUb9LlEgq5b6oI1mkQvnWJ GdE+Q6qaDMsMCYHeSPAl+ntj1PxGBQwYzwyi5KTf95mTPIcCoYYZAT5vkFMoPgXvY8 XUJ26zcDKNRyASugnGuaKBXFh3ijWowtUbYUREsDZTEPyV2i1Nca/Vk2V05Bd9bJlu 3UqcOzcM3cnCA== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 43AABC41613; Mon, 8 Sep 2025 23:01:04 +0000 (UTC) From: bugzilla-daemon@kernel.org To: linux-usb@vger.kernel.org Subject: [Bug 220491] usb_storage connected SD card disconnects/reconnects on resume from suspend Date: Mon, 08 Sep 2025 23:01:04 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: AssignedTo drivers_usb@kernel-bugs.kernel.org X-Bugzilla-Product: Drivers X-Bugzilla-Component: USB X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: paula@alumni.cse.ucsc.edu X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: drivers_usb@kernel-bugs.kernel.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D220491 --- Comment #48 from Paul Ausbeck (paula@alumni.cse.ucsc.edu) --- I spent some time over the weekend instrumenting the kernel so that I could= use kdb to poke around kernel memory. I particularly wanted to examine the cont= ents of the variable reset_resume_delay which turned out to have the value of 0x= 1f4 as I was expecting. I first looked at /dev/mem as a method of reading kernel memory but found that that method has been essentially deprecated and not documented as so. I then instrumented for kdb/kgdb and eventually found tha= t as far as sysrq is concerned, the ativ9 left alt key is different from its rig= ht alt key. I then found that if kdb is active for long enough, kernel stalled, then on= ce the kernel again runs, the SD card reader will disconnect and reconnect similarly to what happens sporadically on resume from suspend. I'm still not certain about this observation. It hasn't happened enough times to be certa= in of stall time requirements or even of correlation. I've just finished disab= ling various systemd daemon watchdog timers that were confusing the issue. If th= is kdb correlation turns out to be real, I think it should be a useful clue. I've got a kdb breakpoint set on the usb_disconnect function. If I can figu= re out how to keep the system from switching virtual consoles when it hits the breakpoint, I will acquire a stack backtrace. --=20 You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.=