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Date:   Fri, 13 Nov 2020 10:08:13 +0800
From:   Wen Gong <wgong@codeaurora.org>
To:     Arend Van Spriel <arend.vanspriel@broadcom.com>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org, kirtika@google.com,
        Johannes Berg <johannes.berg@intel.com>,
        linux-wireless-owner@vger.kernel.org, ath11k@lists.infradead.org,
        ath10k@lists.infradead.org
Subject: Re: [PATCH v2] mac80211: reject/clear user rate mask if not usable
In-Reply-To: <5decc452-7b2a-db1d-c5eb-04ab6bb61553@broadcom.com>
References: <20170308132022.4216-1-johannes@sipsolutions.net>
 <07179008e9369bc81e152009ca85191d@codeaurora.org>
 <5decc452-7b2a-db1d-c5eb-04ab6bb61553@broadcom.com>
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On 2020-11-12 20:49, Arend Van Spriel wrote:
> On 11/12/2020 11:55 AM, Wen Gong wrote:
>> On 2017-03-08 21:20, Johannes Berg wrote:
>>> From: Johannes Berg <johannes.berg@intel.com>
>>> 
> 
> [...]
> 
>>> @@ -2685,6 +2686,21 @@ static int ieee80211_set_bitrate_mask(struct
>>> wiphy *wiphy,
>>>              return ret;
>>>      }
>>> 
>>> +    /*
>>> +     * If active validate the setting and reject it if it doesn't 
>>> leave
>>> +     * at least one basic rate usable, since we really have to be 
>>> able
>>> +     * to send something, and if we're an AP we have to be able to 
>>> do
>>> +     * so at a basic rate so that all clients can receive it.
>>> +     */
>>> +    if (rcu_access_pointer(sdata->vif.chanctx_conf) &&
>>> +        sdata->vif.bss_conf.chandef.chan) {
>>> +        u32 basic_rates = sdata->vif.bss_conf.basic_rates;
>>> +        enum nl80211_band band = 
>>> sdata->vif.bss_conf.chandef.chan->band;
>>> +
>>> +        if (!(mask->control[band].legacy & basic_rates))
>>> +            return -EINVAL;
>> If user want to use “iw wlan0 set bitrates legacy-5 54” to set it to 
>> fixed in 54M and 54M is
>> not basic rate in AP's becaon as example of below, then the iw command 
>> will fail.
> 
> Which was the intent of this change, wasn't it? You want to allow
> anyway or you want a clear error message as to why it fails?
We need to set the tx rate to fixed at a single rate, e.g., 
54M/48M/36M... for a test case.
I do not want a clear error message, I want to the 54M rate pass/set 
success to lower wlan driver.
Then lower wlan driver can handle it.
> 
> Regards,
> Arend