Return-path: Received: from mail-vk0-f52.google.com ([209.85.213.52]:35425 "EHLO mail-vk0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756211AbcGGJaP convert rfc822-to-8bit (ORCPT ); Thu, 7 Jul 2016 05:30:15 -0400 Received: by mail-vk0-f52.google.com with SMTP id v6so12944249vkb.2 for ; Thu, 07 Jul 2016 02:30:15 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1467111448.2493.15.camel@sipsolutions.net> References: <1462430663-9448-1-git-send-email-wnhuang@chromium.org> <1462464478.23962.12.camel@redhat.com> <1462991620.22404.5.camel@redhat.com> <1467111448.2493.15.camel@sipsolutions.net> From: Wei-Ning Huang Date: Thu, 7 Jul 2016 17:30:13 +0800 Message-ID: (sfid-20160707_113106_331469_41D3528A) Subject: Re: [PATCH] cfg80211/nl80211: add wifi tx power mode switching support To: Johannes Berg Cc: Dan Williams , Linux-Wireless , LKML , Sameer Nanda , Todd Broch , davem@davemloft.net, netdev@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi Johannes, Thanks for the reply. You are right that the physical antenna does not change. When I refer to 'calibration data', it actually corresponding to how mwifiex adjust the per-band tx power. For mwifiex, the per-band tx power is pre-calculated based on need, and stored in DT, a vendor command or std nl80211 message is sent to tell the driver to switch between two set of "calibration data". I'm aware that iwl7000 is using a vendor command to do this as well, but instead of pre-calculate required tx power info, the tx value can be passed along with the vendor command message. This patch was sent originally to standardize the requirement of sending a vendor command to the driver (so it'll be a standard nl80211 message). However, we have decided to move along with vendor command for both mwifiex and nl80211, so this patch is not needed anymore. Thanks for the comments! Wei-Ning On Tue, Jun 28, 2016 at 6:57 PM, Johannes Berg wrote: > On Thu, 2016-05-12 at 17:34 +0800, Wei-Ning Huang wrote: >> >> Johannes, I feel like being able to set calibration data at runtime >> is something common to all wireless drivers, so instead of using >> vendor commands what do you think if I pass the calibration data name >> instead of using those magic constants? This way, userspace does not >> need to know the details of what band/range power limit the driver >> supports. It allows for flexible driver side implementation and >> easier for userspace to control. >> > > Sorry - I dropped this thread accidentally. > > I'm not really sure I understand the situation fully, but right now to > me this seems very strange. > > The physical antennas probably don't really change between "clamshell" > and "tablet" mode, do the physical radiation properties change enough > to actually require different *calibration*? To me, that sounds very > strange. > > Assuming they don't really change fundamentally, then I understand the > need to set different power levels, per band/channel/whatever > granularity. But that can be achieved in very different ways, and in > fact if you look at Chrome then for our iwl7000 driver there we do have > a command to do something similar (currently a vendor command, but that > can be changed) without ever changing the *calibration*. > > So to me, the whole premise of the patch is confusing and/or wrong. > > johannes -- Wei-Ning Huang, 黃偉寧 | Software Engineer, Google Inc., Taiwan | wnhuang@google.com | Cell: +886 910-380678