From: Arend van Spriel <arend@broadcom•com>
To: Paul Bolle <pebolle@tiscali•nl>
Cc: Linus Torvalds <torvalds@linux-foundation•org>,
Marcel Holtmann <marcel@holtmann•org>,
Stanislav Yakovlev <stas.yakovlev@gmail•com>,
"Kalle Valo" <kvalo@codeaurora•org>,
Jiri Kosina <jkosina@suse•cz>,
linux-wireless <linux-wireless@vger•kernel.org>,
Network Development <netdev@vger•kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH] Revert "ipw2200: select CFG80211_WEXT"
Date: Mon, 5 Jan 2015 19:22:52 +0100 [thread overview]
Message-ID: <54AAD67C.7090900@broadcom.com> (raw)
In-Reply-To: <1420479510.14308.23.camel@x220>
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
>
next prev parent reply other threads:[~2015-01-05 18:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-03 14:59 [PATCH] Revert "ipw2200: select CFG80211_WEXT" Paul Bolle
2015-01-03 18:02 ` Marcel Holtmann
2015-01-03 18:07 ` Linus Torvalds
[not found] ` <CA+55aFzYSiUkntraMrHEhMzkt35Ft2p9E3cT7ejwQOBDwKvcOg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-03 22:28 ` Paul Bolle
2015-01-05 10:05 ` Johannes Berg
2015-01-05 10:12 ` Jiri Kosina
2015-01-05 10:20 ` Johannes Berg
2015-01-05 10:14 ` Arend van Spriel
2015-01-05 17:38 ` Paul Bolle
2015-01-05 18:22 ` Arend van Spriel [this message]
2015-01-05 18:57 ` Johannes Berg
[not found] ` <1420484224.9459.16.camel-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
2015-01-05 22:05 ` Paul Bolle
2015-01-05 22:13 ` Arend van Spriel
[not found] ` <54AB0C75.1090204-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2015-01-06 8:19 ` Johannes Berg
2015-01-06 8:23 ` Johannes Berg
2015-01-06 13:26 ` Johannes Berg
[not found] ` <1420297188.2397.3.camel-IWqWACnzNjzz+pZb47iToQ@public.gmane.org>
2015-01-06 8:03 ` Kalle Valo
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