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Subject: Re: [PATCH] mt76: mt7615: add support for per-chain signal strength
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To:     Ryder Lee <ryder.lee@mediatek.com>
Cc:     Sean Wang <sean.wang@mediatek.com>,
        Chih-Min Chen <chih-min.Chen@mediatek.com>,
        YF Luo <yf.luo@mediatek.com>, linux-wireless@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Yiwei Chung <yiwei.chung@mediatek.com>,
        linux-mediatek@lists.infradead.org, Roy Luo <royluo@google.com>,
        Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
        Felix Fietkau <nbd@nbd.name>
References: <3912a2863e858f3623ced61737836e42c7b19149.1560071167.git.ryder.lee@mediatek.com>
 <d6cfd2e9-4b2b-36ac-6cae-a34f74204801@newmedia-net.de>
 <1560132590.28258.5.camel@mtkswgap22> <1560140541.5606.12.camel@mtkswgap22>
From:   Sebastian Gottschall <s.gottschall@newmedia-net.de>
Message-ID: <64662021-8e5a-91b5-9afb-3c9005564d19@newmedia-net.de>
Date:   Mon, 10 Jun 2019 06:47:39 +0200
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okay. curious is, that my variant works with sane results too.
i will test your variant and check the results

Sebastian

Am 10.06.2019 um 06:22 schrieb Ryder Lee:
> On Mon, 2019-06-10 at 10:09 +0800, Ryder Lee wrote:
>> On Sun, 2019-06-09 at 16:44 +0200, Sebastian Gottschall wrote:
>>> according to my findings
>>>
>>> MT_RXV4_RCPI1 is part of rx descriptor 4 and not 3
>>> so it must be rxdg4 = rxd[4] etc.
>> RXV start from 1 in the code.
>>
>> That is: RXV1 <-> rxdg0, RXV2 <-> rxdg1 ...so RXV4 <-> rxdg3
>>
>>> however rxdg3 contains MT_RXV3_IB_RSSIRX which can be used for signal calculation.
>>> i already wrote a similar code for this driver which i sended to felix a long time ago.
>>> my variant looks like
>>>                   status->signal = (FIELD_GET(MT_RXV3_IB_RSSIRX, rxdg3) - 220) / 2;
>>>                   status->chain_signal[0] = (FIELD_GET(MT_RXV4_RCPI0, rxdg4) - 220) / 2;
>>>                   status->chain_signal[1] = (FIELD_GET(MT_RXV4_RCPI1, rxdg4) - 220) / 2;
>>>                   status->chain_signal[2] = (FIELD_GET(MT_RXV4_RCPI2, rxdg4) - 220) / 2;
>>>                   status->chain_signal[3] = (FIELD_GET(MT_RXV4_RCPI3, rxdg4) - 220) / 2;
> mt7615 actually doesn't use in-band RSSI for signal calculation, but it
> occurs to me that i should modify the code to compare per-chain's
> signal. Something like this:
>
> 		status->chain_signal[0] = to_rssi(MT_RXV4_RCPI0, rxdg3);
> 		status->chain_signal[1] = to_rssi(MT_RXV4_RCPI1, rxdg3);
> 		status->chain_signal[2] = to_rssi(MT_RXV4_RCPI2, rxdg3);
> 		status->chain_signal[3] = to_rssi(MT_RXV4_RCPI3, rxdg3);
> 		status->signal = status->chain_signal[0];
>
> 		switch (status->chains) {
> 		case 0xf:
> 			status->signal = max(status->signal,
> 					     status->chain_signal[3]);
> 		case 0x7:
> 			status->signal = max(status->signal,
> 					     status->chain_signal[2]);
> 		case 0x3:
> 			status->signal = max(status->signal,
> 					     status->chain_signal[1]);
> 			break;
> 		default:
> 			break;
> 		}
>
>
> I could send a v2 or you can take care of that.
>
> Ryder
>
>