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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F358C433F5 for ; Tue, 5 Oct 2021 11:06:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A17F61251 for ; Tue, 5 Oct 2021 11:06:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233835AbhJELIi (ORCPT ); Tue, 5 Oct 2021 07:08:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:45652 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233449AbhJELIh (ORCPT ); Tue, 5 Oct 2021 07:08:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D735761139; Tue, 5 Oct 2021 11:06:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633432007; bh=rTNNhWJqsVcBG/ZVwbPHyK3Hc5Td838t+NE0/luBO0k=; h=References:From:To:Cc:Subject:Date:In-reply-to:From; b=hBDC6ZpKFybCS3A2aITRBx8AIIYHVmPJ3z4hxPmsDh8GaOXM/bNFlfRPnY6xU3clu ZrSXyenbp6jrXDXOpuZF16gTyb+Asm/FnXY4qlc/ujOwmGAdemcVuYKEjP5cnBzu/C w1V0IA9fs0KcpAUDQBV8zJY8vjTkFYNWZ0+K2COI/ltK9aDfJMcVqJl14k8IxH40Uw HcWtrYZQe8zlxNpbQDbStBFk7yHTFq8960Z6WvNgE/epz2+zpBaoYowWR2dEaPGgMn tzBTYHh83Jf33SsC2t4VUYai9wit1k6T6DI0L6MkY8QztVxWJzM28Pxfkn/SDPxJPn KWPzr78qypI5w== References: <87pn261h4c.fsf@kernel.org> <20211003201355.24081-1-m.grzeschik@pengutronix.de> User-agent: mu4e 1.6.6; emacs 27.2 From: Felipe Balbi To: Greg KH Cc: Laurent Pinchart , Michael Grzeschik , linux-usb@vger.kernel.org, hverkuil@xs4all.nl, m.tretter@pengutronix.de, linux-media@vger.kernel.org Subject: Re: [RESEND PATCH v4] usb: gadget: uvc: fix multiple opens Date: Tue, 05 Oct 2021 14:06:22 +0300 In-reply-to: Message-ID: <87a6jnzq64.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Greg KH writes: > On Tue, Oct 05, 2021 at 02:53:48AM +0300, Laurent Pinchart wrote: >> Hi Michael, >> >> Thank you for resending this. >> >> On Sun, Oct 03, 2021 at 10:13:55PM +0200, Michael Grzeschik wrote: >> > From: Thomas Haemmerle >> > >> > Currently, the UVC function is activated when open on the corresponding >> > v4l2 device is called. >> > On another open the activation of the function fails since the >> > deactivation counter in `usb_function_activate` equals 0. However the >> > error is not returned to userspace since the open of the v4l2 device is >> > successful. >> > >> > On a close the function is deactivated (since deactivation counter still >> > equals 0) and the video is disabled in `uvc_v4l2_release`, although the >> > UVC application potentially is streaming. >> > >> > Move activation of UVC function to subscription on UVC_EVENT_SETUP >> > because there we can guarantee for a userspace application utilizing >> > UVC. >> > Block subscription on UVC_EVENT_SETUP while another application already >> > is subscribed to it, indicated by `bool func_connected` in >> > `struct uvc_device`. >> > Extend the `struct uvc_file_handle` with member `bool is_uvc_app_handle` >> > to tag it as the handle used by the userspace UVC application. >> >> Reflowing the paragraph would be nice (this could be done when applying >> the patch, or not at all). >> >> > With this a process is able to check capabilities of the v4l2 device >> > without deactivating the function for the actual UVC application. >> > >> > Reviewed-By: Michael Tretter >> > Signed-off-by: Thomas Haemmerle >> > Signed-off-by: Michael Tretter >> > Signed-off-by: Michael Grzeschik >> >> Reviewed-by: Laurent Pinchart >> >> Felipe, please let me know if you want me to take this in my tree and >> issue a pull request, otherwise I'll assume you'll pick it up. > > I'll pick it up now, thanks. I guess it's too late for an Ack. FWIW: Acked-by: Felipe Balbi -- balbi