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 17E3DC433EF for ; Fri, 19 Nov 2021 08:31:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4C2461AD2 for ; Fri, 19 Nov 2021 08:31:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234147AbhKSIew (ORCPT ); Fri, 19 Nov 2021 03:34:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229633AbhKSIev (ORCPT ); Fri, 19 Nov 2021 03:34:51 -0500 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8802EC061574 for ; Fri, 19 Nov 2021 00:31:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: Content-Type:References:In-Reply-To:Date:To:From:Subject:Message-ID:Sender: Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=s/szsktVZIkmXcxmmuot84sy9JZdEWq/1m0i5Lod250=; t=1637310710; x=1638520310; b=WguTdVSRZe2MH2LU3BeUHWJZKnDDZneCcCmGT0A4JBXWf4f pxE+aip4jy7XUl17VDhcvTwBz4cKXvbxeffp1blAc1Ag5I+KHbyeTYJMKqiymFwWShn5QNPZzbmsk m+cnxunCkB5fu9tJbVOWBlc9a5yjRGVG1ajrdYeFMxn4mMpkrKHZ497UhS6W+MC26uNO5JrHwImXY X29huRQWXR38NtXE4BN1K3LfXbkZSu+S4+6UqtM0VXQ/7jzKqJ7EyA2HrTvJjr3vp1mCgsgdYYd94 t15egrhZ92orS7EVAlE6Aw/I/apeREBZkKv9VTKHFibS/+IgEAmvY0nnl6/L84GQ==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.95) (envelope-from ) id 1mnzJD-00HNEm-Pz; Fri, 19 Nov 2021 09:31:47 +0100 Message-ID: <47ba74aa23a5c4fb42660d5b40e974c24acf24bf.camel@sipsolutions.net> Subject: Re: Adding CMD_SET_CHANNEL for station iftypes From: Johannes Berg To: James Prestwood , "linux-wireless@vger.kernel.org" Date: Fri, 19 Nov 2021 09:31:47 +0100 In-Reply-To: <2b18f86924c3d64437aa139f6401ee2e7705eeb0.camel@gmail.com> References: <2b18f86924c3d64437aa139f6401ee2e7705eeb0.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.1 (3.42.1-1.fc35) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-malware-bazaar: not-scanned Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Thu, 2021-11-18 at 16:11 -0800, James Prestwood wrote: > Hi, > > I see CMD_SET_CHANNEL is only supported for AP-type iftypes (AP, > P2P_GO, etc). While this definitely makes sense in most cases, > protocols like p2p/dpp require going off channel for an undetermined > amount of time. > > I could go into the exact scenarios but in short your REMAIN_ON_CHANNEL > could end at very inconvenient times. > > Specifically when a station is not associated to any AP is there any > harm in allowing CMD_SET_CHANNEL? Is this purely a software limitation > or do drivers not allow this? > > If this sounds reasonable (and possible) I don't think this *works* because you don't have a way to say "I want to now go back to idle". And sitting on a channel arbitrarily can consume quite a bit of power. So you'd have to add an API to cancel it again, but then realistically we'd probably want to be able to cancel it if userspace forgets (ie. give it a timeout), at which point it's basically equivalent to a longer-than-you-needed remain-on-channel that you cancel after you're done? johannes