From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-gw2-out.broadcom.com ([216.31.210.63]:51577 "EHLO mail-gw2-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932093AbbAESWz (ORCPT ); Mon, 5 Jan 2015 13:22:55 -0500 Message-ID: <54AAD67C.7090900@broadcom.com> (sfid-20150105_192337_764893_E2F363F2) Date: Mon, 5 Jan 2015 19:22:52 +0100 From: Arend van Spriel MIME-Version: 1.0 To: Paul Bolle CC: Linus Torvalds , Marcel Holtmann , Stanislav Yakovlev , "Kalle Valo" , Jiri Kosina , linux-wireless , Network Development , Linux Kernel Mailing List Subject: Re: [PATCH] Revert "ipw2200: select CFG80211_WEXT" References: <1420297188.2397.3.camel@tiscali.nl> <1420324124.9624.60.camel@x220> <54AA641C.7050307@broadcom.com> <1420479510.14308.23.camel@x220> In-Reply-To: <1420479510.14308.23.camel@x220> Content-Type: text/plain; charset="UTF-8"; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 01/05/15 18:38, Paul Bolle wrote: > On Mon, 2015-01-05 at 11:14 +0100, Arend van Spriel wrote: >> On 01/03/15 23:28, Paul Bolle wrote: >>> Side note: am I correct in thinking that there's some successor to >>> CFG80211_WEXT and that the ipw2200 driver could, at least in theory, be >>> ported to that successor? (ipw2200 hardware appears to be a bit old, so >>> probably no one would care enough to actually do that.) >>> net/wireless/kconfig doesn't mention anything like that, so probably I'm >>> just confused. >> >> ipw2200 is a WEXT driver using some wext functionality (and struct >> wiphy) provided by cfg80211 hence it needs CFG80211_WEXT. I guess that >> is what makes it confusing. > > It doesn't help that I hardly know anything about mac80211, cfg80211 and > nl80211 (and lib80211 for that matter). To me these are mostly just > names that end in 80211. Grapjas ;-) cfg80211 provides thin-layer API for fullmac drivers (running 802.11 stack on the device) and mac80211-based drivers (running 802.11 stack in kernel). > Anyhow, concerning, CFG80211_WEXT: it seems the only functionality > provided by that symbol that ipw2200 uses directly is > cfg80211_wext_giwname(). Perhaps ipw2200 could have a private version of > that function, something like ipw2100's ipw2100_wx_get_name(). Should be > trivial to implement (ie, it could take _me_ a day or two). Indeed or even an hour or two. > But perhaps ipw2200 uses CFG80211_WEXT _indirectly_ too. Ie, in > net/wireless/core.c I stumbled on > #ifdef CONFIG_CFG80211_WEXT > rdev->wiphy.wext =&cfg80211_wext_handler; > #endif This is the "wext compatibility" being enabled for any cfg80211 or mac80211 based driver. > > But I net/wireless/wext-core.c I then found > #ifdef CONFIG_CFG80211_WEXT > if (dev->ieee80211_ptr&& dev->ieee80211_ptr->wiphy) > handlers = dev->ieee80211_ptr->wiphy->wext; > #endif wext-core is the WEXT framework and here it extracts WEXT handlers from a cfg80211/mac80211-based driver that are store in wiphy structure. > #ifdef CONFIG_WIRELESS_EXT > if (dev->wireless_handlers) > handlers = dev->wireless_handlers; > #endif Here wext-core extracts WEXT handlers from a WEXT driver. struct net_device::wireless_handlers is only defined for CONFIG_WIRELESS_EXT. > (There's much more to discover about WEXT, of course.) Anyhow, IPW2200 > uses both CFG80211_WEXT and WIRELESS_EXT and cfg80211_wext_handler and > ipw2200's wireless_handlers appear to cover the same set of IOCTLS (one > exception: SIOCSIWPMKSA). So by now I'm really puzzled how this all fits > together. I think ipw2200 is a bit of both worlds indeed adopting the use of struct wiphy and wiphy_register() call. That seems to suggest it is a cfg80211 driver, but it does not register any cfg80211 driver callbacks (see libipw_config_ops in libipw_module.c). So it overrides the WEXT ioctls because it needs that to interact with the device. Regards, Arend > Thanks, > > > Paul Bolle >