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From: "Luis R. Rodriguez" <lrodriguez@atheros.com>
To: Felix Fietkau <nbd@openwrt.org>
Cc: Bruno Randolf <br1@einfach.org>,
	"johannes@sipsolutions.net" <johannes@sipsolutions.net>,
	"linville@tuxdriver.com" <linville@tuxdriver.com>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH v4 1/3] cfg80211: Add nl80211 antenna configuration
Date: Wed, 28 Jul 2010 15:14:00 -0700	[thread overview]
Message-ID: <AANLkTinG1tVXfKn0rdU2v+xXvQU1S+fcxorkxyCVFCrH@mail.gmail.com> (raw)
In-Reply-To: <4C50A9B9.5070708@openwrt.org>

On Wed, Jul 28, 2010 at 3:05 PM, Felix Fietkau <nbd@openwrt.org> wrote:
> On 2010-07-28 11:39 PM, Luis R. Rodriguez wrote:
>> On Wed, Jul 28, 2010 at 02:26:35PM -0700, Felix Fietkau wrote:
>>> We don't need any special case handling for this at all. Drivers already
>>> calculate their HT capabilities based on the number of available chains.
>>> Once the antenna selection stuff is actually used, they will have some
>>> internal information about which chains have how many antennas.
>>>
>>> The reason why we can ignore *all* of this stuff for the API is simple:
>>> We only need to refactor the code to calculate these settings based on
>>> effective chainmask / antenna mask instead of pure hardware capability.
>>>
>>> The effective chainmask / antenna mask is basically the same as the
>>> hardware settings, except that it gets masked with the values that are
>>> configured through this API. That leaves us with something that's easy
>>> to configure, easy to implement for drivers, and doesn't need special
>>> case stuff for various 802.11n features.
>>
>> Consider the case of an already associated STA in 3x3 mode, and someone
>> uses this API to limit it to a 1 stream 1x1 chaimask setting using
>> only one antenna. How would the AP find out about this RX setting
>> from the STA? Are we going to deny mucking with this prior to association?
>> What about if you're the AP?
>>
>> If you are using STBC and the user tunes the device to 1 stream 1x1 chainmask
>> settings, who deals with the required adaptations?
> I think we should simply not accept runtime modifications of this stuff.
> The user should bring down the interface, change the value, then bring
> it back up again. That allows the driver to recalculate all the HT stuff
> based on the updated chainmask/antenna mask without special cases.

Sound good, so based on the passed info, will cfg80211 lift off STBC
capability settings if 1 stream 1x1 settings are used?

  Luis

  reply	other threads:[~2010-07-28 22:14 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-27  9:47 [PATCH v4 0/3] Antenna configuration Bruno Randolf
2010-07-27  9:48 ` [PATCH v4 1/3] cfg80211: Add nl80211 antenna configuration Bruno Randolf
2010-07-27 10:05   ` Johannes Berg
2010-07-28  2:03     ` Bruno Randolf
2010-07-27 16:19   ` Luis R. Rodriguez
2010-07-27 16:39     ` Felix Fietkau
2010-07-27 16:47       ` Luis R. Rodriguez
2010-07-28  2:06         ` Bruno Randolf
2010-07-28 17:24           ` Luis R. Rodriguez
2010-07-28 17:50             ` Felix Fietkau
2010-07-28 21:15               ` Luis R. Rodriguez
2010-07-28 21:26                 ` Felix Fietkau
2010-07-28 21:39                   ` Luis R. Rodriguez
2010-07-28 22:05                     ` Felix Fietkau
2010-07-28 22:14                       ` Luis R. Rodriguez [this message]
2010-07-29  0:10                       ` Luis R. Rodriguez
2010-07-29  2:11             ` Bruno Randolf
2010-07-29 15:09               ` Luis R. Rodriguez
2010-08-02  3:59                 ` Bruno Randolf
2010-08-02  5:31                   ` Luis R. Rodriguez
2010-07-27  9:48 ` [PATCH v4 2/3] mac80211: Add " Bruno Randolf
2010-07-27  9:48 ` [PATCH v4 3/3] ath5k: Add support for " Bruno Randolf

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