From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B22072F7F1B; Wed, 12 Aug 2026 00:18:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786493912; cv=none; b=VAGExgiGGv5cGhXq8SUoR6PlLM57P9ntvMm5nDe+pxtMCrfJqWUjWpnLkZfqPUU6BC5pPS9gxCksQ290s8UCxKf9wHfFKCv5j/hzEDPBdlRjVmTRYxKaUD4EkFJJ3xwTzuVDgrNCheaP9GcmSqrZ108ojaMT3eW+CHDRc0Sg+xo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786493912; c=relaxed/simple; bh=9AFnzOxbS0WIaXEtDBDqzEjA2xW8uZJrvsoRNhJ6ucM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TcEtDWIjv47rqH7jaCvHUyMhmh8s19w9iYP2JIKo3IDciqB/kKHcS54MK4sjnpj2GEcLIKHNEBh9hRu2t45BOAnjW2uFZt4OtIWgJR572VgTX9CDnXUFttHOqWX2IjWfpZ4aMV4pZC/kYzfw/d2hB4FiOtmbAz6xNP2iJp2i6ek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pc98JJvO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pc98JJvO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DFC21F00A3A; Wed, 12 Aug 2026 00:18:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786493911; bh=Fhohq0YeApVJZMAIKOTVHtLwtvMpDfkKYE3O8L336Jk=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=pc98JJvO2EZyEqEEqxWqEkJG+Lxk+0TMaCPWNnVfwycHtg2i/dxthyYpWf/QEKrfd w3he32bksPDF9YZK+A5+1KIbkA43qX0tC+UdL87+n/bR1Xvh9Otb3NQFMc2UvXFpES irXqTeguQmCMm8ZqJoGQXePcu5uwkeQir8Pd8y1U= Date: Wed, 12 Aug 2026 09:16:58 +0900 From: Greg Kroah-Hartman To: Junzhong Pan Cc: Thinh Nguyen , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, troy.mitchell@linux.spacemit.com, peixin.xie@linux.spacemit.com Subject: Re: [RFC PATCH] usb: dwc3: core: resume xHCI child on runtime resume in host mode Message-ID: <2026081244-crushed-headband-dc5a@gregkh> References: <20260811090817.109350-1-panjunzhong@linux.spacemit.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260811090817.109350-1-panjunzhong@linux.spacemit.com> On Tue, Aug 11, 2026 at 05:08:17PM +0800, Junzhong Pan wrote: > USB controller runtime suspend halts the controller on disconnection. > It relies on platforms with custom connection notification to start > the controller again. > > The host branch of dwc3_runtime_resume() does nothing currently. There > are two paths that can trigger a runtime resume of the dwc3 core in > host mode: > > (a) Wake lands on the xHCI child (DT platforms, e.g. Qualcomm, i.MX8MP) > A platform wakeup IRQ fires and the glue handler calls > pm_runtime_resume(&xhci->dev). Runtime PM walks upward, resumes > the dwc3 parent first, then resumes xHCI. Both wake correctly. > > (b) Wake lands on the dwc3 parent (ACPI platforms) > When an ACPI Notify(ACPI_NOTIFY_DEVICE_WAKE) targets the dwc3 > parent device -- for example via a Generic Event Device on a > hardware-reduced platform where dwc3 is enumerated as an ACPI > device without a glue driver -- the ACPI core turns this into > pm_request_resume(dwc3_dev). Runtime PM does not propagate resume > downward, so the xHCI child stays suspended. Root hub polling is > never re-armed, and a device plugged in while suspended is silently > dropped. > > This patch fills in the host branch to cover case (b) by requesting an > async resume of the xHCI child so xhci_resume() can restore the port > state machine and re-arm root hub polling. Async is required to avoid > deadlocking on the parent's own rpm_resume() re-entry. > > Signed-off-by: Junzhong Pan > --- > base-commit: d58772d8520c7ef247c4b95c9bd76d3a25da9ff5 > drivers/usb/dwc3/core.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) Did you get LLM help with creating this patch? thanks, greg k-h