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Subject: Re: [RFC v2 4/6] mac80211: add utility function for tx_rate -
 rate_info conversion
From:   Jonas Jelonek <jelonek.jonas@gmail.com>
In-Reply-To: <f364ace23f73e90f9cf62b5c8238e78599b6b7ab.camel@sipsolutions.net>
Date:   Thu, 19 Jan 2023 15:34:52 +0100
Cc:     linux-wireless@vger.kernel.org, Felix Fietkau <nbd@nbd.name>
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References: <20220920104032.496697-1-jelonek.jonas@gmail.com>
 <20220920104032.496697-5-jelonek.jonas@gmail.com>
 <64731257b957f50b0f66e4d2fcd8c24dea8d70ff.camel@sipsolutions.net>
 <9AE44A41-6357-4F3A-BF75-8E3B0A381E9B@gmail.com>
 <f364ace23f73e90f9cf62b5c8238e78599b6b7ab.camel@sipsolutions.net>
To:     Johannes Berg <johannes@sipsolutions.net>
Precedence: bulk


> On 19. Jan 2023, at 12:35, Johannes Berg <johannes@sipsolutions.net> wrote:
> 
> On Thu, 2023-01-19 at 12:31 +0100, Jonas Jelonek wrote:
>>> On 12. Jan 2023, at 11:26, Johannes Berg <johannes@sipsolutions.net>
>>> wrote:
>>> 
>>>> +void ieee80211_rate_get_rate_info(const struct ieee80211_tx_rate *rate,
>>>> + 							struct wiphy *wiphy, u8 band,
>>>> +  							struct rate_info *rate_info)
>>>> +{
>>>> +  	memset(rate_info, 0, sizeof(struct rate_info));
>>>> +
>>>> +  	if (rate->flags & IEEE80211_TX_RC_MCS) { /* 802.11n */
>>>> +  		rate_info->flags |= RATE_INFO_FLAGS_MCS;
>>>> +  		rate_info->mcs = rate->idx;
>>>> +  	} else if (rate->flags & IEEE80211_TX_RC_VHT_MCS) { /* 802.11ac */
>>>> +  		rate_info->flags |= RATE_INFO_FLAGS_VHT_MCS;
>>>> +  		rate_info->mcs = ieee80211_rate_get_vht_mcs(rate);
>>>> +  		rate_info->nss = ieee80211_rate_get_vht_nss(rate);
>>>> +  } else { /* 802.11a/b/g */
>>> 
>>> what about HE/EHT?
>> 
>> ieee80211_tx_rate uses an s8 for rate/MCS index, so only up to VHT
>> rates fit in there.
>> For rates above VHT, rate_info is needed, thus are are no HE/EHT rates
>> occuring in
>> ieee80211_tx_rate. Same applies to your comment on the hwsim
>> conversion.
> 
> I guess I should've read the commit message more closely ;-)
> 
> But please add kernel-doc to the function; both in general it'd be good
> to have, and in particular explaining that this is more for older
> drivers I guess?

I will add that in my next RFC version to make sure this is clear.

Jonas