Re: [PATCH v2 2/2] mac80211: store tx power value from user to station

From: Ben Greear <greearb@candelatech.com>
To: Ashok Raj Nagarajan <arnagara@codeaurora.org>
Cc: Ashok Raj Nagarajan <arnagara@qti.qualcomm.com>,
	linux-wireless@vger.kernel.org, johannes@sipsolutions.net,
	ath10k@lists.infradead.org
Subject: Re: [PATCH v2 2/2] mac80211: store tx power value from user to station
Date: Wed, 1 Feb 2017 09:32:39 -0800	[thread overview]
Message-ID: <35c617ff-c07a-b221-5742-b1487618bce7@candelatech.com> (raw)
In-Reply-To: <7584a5235b49b7799a2c15f91fb03794@codeaurora.org>

On 02/01/2017 09:29 AM, Ashok Raj Nagarajan wrote:
> On 2017-02-01 00:30, Ben Greear wrote:
>> On 01/31/2017 10:41 AM, Ashok Raj Nagarajan wrote:
>>> This patch introduce a new driver callback drv_sta_set_txpwr. This API will
>>> copy the transmit power value passed from user space and call the driver
>>> callback to set the tx power for the station.
>>>
>>> Signed-off-by: Ashok Raj Nagarajan <arnagara@qti.qualcomm.com>
>>> ---
>>>  include/net/mac80211.h    |  6 ++++++
>>>  net/mac80211/cfg.c        |  7 +++++++
>>>  net/mac80211/driver-ops.c | 21 +++++++++++++++++++++
>>>  net/mac80211/driver-ops.h |  5 +++++
>>>  net/mac80211/trace.h      | 27 +++++++++++++++++++++++++++
>>>  5 files changed, 66 insertions(+)
>>>
>>> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
>>> index 5345d35..e059d5a 100644
>>> --- a/include/net/mac80211.h
>>> +++ b/include/net/mac80211.h
>>> @@ -1777,6 +1777,8 @@ struct ieee80211_sta_rates {
>>>   *    This is defined by the spec (IEEE 802.11-2012 section 8.3.2.2 NOTE 2).
>>>   * @support_p2p_ps: indicates whether the STA supports P2P PS mechanism or not.
>>>   * @max_rc_amsdu_len: Maximum A-MSDU size in bytes recommended by rate control.
>>> + * @txpwr: indicates the tx power, in dBm, to be used when sending data frames
>>> + *    to the STA. Value of 0 means, automatic (default) tx power.
>>
>> Atheros NICs use 1/2 dBm increments internally, so maybe pass down mBm
>> to the driver so you don't
>> loose the granularity?  (Other NICs may potentially have even finer control.)
>>
>
> ath10k firmware expects values to be in dBm and the calculations regarding 1/2 dBm is taken care in firmware.

Other drivers may want more precision, so I still think you should store this in mBm instead
of throwing away precision in the API.

A new and improved ath10k firmware may support 1/2 dBm units directly, for instance.

Thanks,
Ben

>
> Thanks,
> Ashok
>> Thanks,
>> Ben
>

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com