From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 1787E22423A; Fri, 2 Oct 2026 01:18:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790903920; cv=none; b=dVjBTEVHCZKLQ5Tv3CFm3nqEaAlr6SSsGYI2B9f18zO2kUUp+6lHaklQC/YH6YrGudntFhN4F/jNRbVvAO6L0P/m+KoILSFJzv0W2ZXoAyNMhjpucm5w6DtWtV37NgNeW6Wz+aRB/WxrICAJgvgUoE6zpIDOgP6uSXS8JNKGyeU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790903920; c=relaxed/simple; bh=DimN0iZw0iBl0ePgNYyHdsW2Ta+q9KYFkw6gX5WiHQQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tD13hQz0nDWDSZWCfFv7pg5+4Owjj7K+wdp8Dqwn/0PRgZbtv2v5aB0e21r4rJWl3O0DW1AfEDBJz/tvg1xRrTVaWd9BMKUcpMBpmBQNuIYAlyu+Qfj+NnVD3INaKiHPIHnG3u6/X6DC2ObmhR2uAENfxF1aez2ehCbxkl055aM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=Q/lPxyRs; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="Q/lPxyRs" Received: from killaraus.ideasonboard.com (2001-14ba-70f3-e800--a06.rev.dnainternet.fi [IPv6:2001:14ba:70f3:e800::a06]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 856E5227; Fri, 2 Oct 2026 03:16:44 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1790903804; bh=DimN0iZw0iBl0ePgNYyHdsW2Ta+q9KYFkw6gX5WiHQQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Q/lPxyRsVP918+X5+y+4p3sOId+LimE6+DD1AYbicfge5XpEqkAuaORARDmksFNha r92eby6wdoGRtgBnVIJpXyHhZThDsloigUUJIv1fiK/6o31QH/q36t52Hhwkzw4dSY j1P3fJFHLLMb6HvhpB6NIn640lnkubvcGzWur+2Q= Date: Fri, 2 Oct 2026 04:18:35 +0300 From: Laurent Pinchart To: raoxu Cc: hansg@kernel.org, mchehab@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] media: uvcvideo: preserve status URB interval on resubmit Message-ID: <20261002011835.GA93319@killaraus.ideasonboard.com> References: <20261001231856.GB9061@killaraus.ideasonboard.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=utf-8 Content-Disposition: inline In-Reply-To: <20261001231856.GB9061@killaraus.ideasonboard.com> On Fri, Oct 02, 2026 at 02:18:56AM +0300, Laurent Pinchart wrote: > On Thu, Aug 13, 2026 at 03:46:32PM +0800, raoxu wrote: > > From: Xu Rao > > > > usb_fill_int_urb() takes an endpoint interval value and stores the > > period expected by usb_submit_urb() in urb->interval. For high-speed > > and SuperSpeed interrupt endpoints, it converts the logarithmic > > descriptor encoding to the corresponding microframe period. > > > > The UVC status URB is initialized once in uvc_status_init(), including > > the UVC_QUIRK_STATUS_INTERVAL adjustment required by high-speed devices > > that report bInterval using the old full-speed convention. The first > > submission therefore carries the intended interval. > > > > Both status resubmit paths, however, overwrite urb->interval with the > > raw endpoint bInterval before submitting the same URB again. On > > high-speed and SuperSpeed devices this mixes the descriptor encoding > > with the already converted URB interval representation. For devices > > using UVC_QUIRK_STATUS_INTERVAL it also deterministically discards the > > quirk adjustment after the first status completion, making the > > workaround effective only for the initial submission. > > > > This has been easy to miss because the initial status submission is > > correct, full-speed interrupt endpoints do not have the same > > logarithmic encoding mismatch, and the status endpoint carries > > relatively infrequent control and streaming notifications rather than > > the video payload itself. The problem only appears after the status URB > > has completed and is resubmitted, and the externally visible effect > > also depends on how the host controller handles the resulting period. > > > > Do not restore bInterval when resubmitting the status URB. Reuse the > > interval established by usb_fill_int_urb() and usb_submit_urb(), which > > also preserves the quirk-adjusted value. No additional state or > > interval conversion is needed because the same URB is being reused. > > > > This commit message is also very long and has a large amount of > irrelevant, when not borderline incorrect, information. Is this missing > an Assisted-by tag ? > > > Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver") > > Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") Also, how is stable supposed to make sense of this ? > > Cc: stable@vger.kernel.org > > Signed-off-by: Xu Rao > > --- > > drivers/media/usb/uvc/uvc_ctrl.c | 1 - > > drivers/media/usb/uvc/uvc_status.c | 1 - > > 2 files changed, 2 deletions(-) > > > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > > index 3ca108b83f1d..6552f541aa0d 100644 > > --- a/drivers/media/usb/uvc/uvc_ctrl.c > > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > > @@ -2196,7 +2196,6 @@ static void uvc_ctrl_status_event_work(struct work_struct *work) > > return; > > > > /* Resubmit the URB. */ > > - w->urb->interval = dev->int_ep->desc.bInterval; > > ret = usb_submit_urb(w->urb, GFP_KERNEL); > > if (ret < 0) > > dev_err(&dev->intf->dev, > > diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c > > index b632cf5e3fe9..680c6c7f4ad7 100644 > > --- a/drivers/media/usb/uvc/uvc_status.c > > +++ b/drivers/media/usb/uvc/uvc_status.c > > @@ -245,7 +245,6 @@ static void uvc_status_complete(struct urb *urb) > > } > > > > /* Resubmit the URB. */ > > - urb->interval = dev->int_ep->desc.bInterval; > > ret = usb_submit_urb(urb, GFP_ATOMIC); > > if (ret < 0) > > dev_err(&dev->intf->dev, -- Regards, Laurent Pinchart