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 X-Spam-Level: X-Spam-Status: No, score=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60D43C433B4 for ; Fri, 21 May 2021 11:40:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 41C6B613DF for ; Fri, 21 May 2021 11:40:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234806AbhEULl3 (ORCPT ); Fri, 21 May 2021 07:41:29 -0400 Received: from gofer.mess.org ([88.97.38.141]:37575 "EHLO gofer.mess.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234235AbhEULlV (ORCPT ); Fri, 21 May 2021 07:41:21 -0400 Received: by gofer.mess.org (Postfix, from userid 1000) id 7A7DCC636F; Fri, 21 May 2021 12:39:54 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mess.org; s=2020; t=1621597194; bh=nNH5XtoC9UBrAOPRpJUJWpS23rVXETysVj2i/d51D0A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=P+4WBeMiu084vUEE/3HYe+wchXQ7CoiJE4PmxI9sktnApV3/9FWvmhaig16AOhMPv hvAM7mxe6sNjWTbkwFMRbxZXNGs6vu5JS+YSqbiHinMTnVAXg2R2ckrcJUJ8dlRpTh X+4cHxVBFp5l2N4cZGZq4hSGwebNwnuv/40q75P6pQ9KG1N7nyNzJkMKMRy0ZVDdgU gg5FQGi/UtOPQs7ApMOpJU4G/ptquuB/36r/AP5vIQk6phM3BEZaJVRY1Q1bHgnpJS KD/FS74abHH9rudh8/KIQYjk3xCCXBzUkP/HEqe7xO0bI9GX03UmiUAjYedIdE9NZG oTVdfoFEOo3mQ== Date: Fri, 21 May 2021 12:39:54 +0100 From: Sean Young To: Johan Hovold Cc: linux-media@vger.kernel.org, linux-usb@vger.kernel.org, Greg Kroah-Hartman , Jon Rhees , Oliver Neukum Subject: Re: [PATCH v3 0/3] IR driver for USB-UIRT device Message-ID: <20210521113954.GA21275@gofer.mess.org> References: <20210511103219.GA13769@gofer.mess.org> <20210515092226.GA31801@gofer.mess.org> <20210517103522.GA4644@gofer.mess.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Thu, May 20, 2021 at 03:31:34PM +0200, Johan Hovold wrote: > On Mon, May 17, 2021 at 11:35:22AM +0100, Sean Young wrote: > > On Mon, May 17, 2021 at 11:30:39AM +0200, Johan Hovold wrote: > > > On Sat, May 15, 2021 at 10:22:26AM +0100, Sean Young wrote: > > > > The other nice thing is that IR TX feeds data from an urb interrupt handler, > > > > so you don't need to rely userspace being scheduled quickly enough to feed > > > > more data before the device runs out. > > > > > > The tty layer and tty drivers provide write buffering so that need not > > > be an issue. > > > > Ok. I don't know what the size of the write buffer is or what the maximum > > TX size is; the IR device supports infinite streaming. > > Our tty drivers typically have at least a 4k buffer for transmission. > Surely that should be enough for a remote control but perhaps there are > other more demanding applications? That's more than enough. The most demanding consumer IR I know of, is an air conditioner which encodes temperature and a few others things. That's a maximum of 439 pulse/spaces which should into 1k. > > > > Thanks for that pointer. Judging from a quick look, the new driver > > > appears to based on this one. By abstracting the serial interface bits > > > in a generic RC serdev/ldisc driver you may be able reuse more code, > > > even if I'm not in a position to judge how much of the IR protocol bits > > > that can be shared. > > > > Yes, I agree. Once hotplugging is in place. If you have patches for that, > > please CC me and I can see if will work for IR drivers. > > Let's hope someone steps up to fund that work then. I'm just a volunteer. I've literally never heard anything about kernel work being funded by anyone. Would you mind giving a brief summary what is needed to implement hotplugging for serdev? I get the impression it's not a lot of work, but I'm probably missing something obvious. Sean