Re: [PATCH] mt76: mt7615: add support for per-chain signal strength reporting

[Ryder Lee <ryder.lee-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>]

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;

> Am 09.06.2019 um 11:09 schrieb Ryder Lee:
> > Fill in RX status->chain_signal to avoid empty value.
> >
> > Signed-off-by: Ryder Lee <ryder.lee-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> > ---
> >   .../net/wireless/mediatek/mt76/mt7615/mac.c   | 30 ++++++++++++++++++-
> >   .../net/wireless/mediatek/mt76/mt7615/mac.h   |  5 ++++
> >   2 files changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mac.c b/drivers/net/wireless/mediatek/mt76/mt7615/mac.c
> > index b60d42b5923d..9ee83ea11b8c
> > --- a/drivers/net/wireless/mediatek/mt76/mt7615/mac.c
> > +++ b/drivers/net/wireless/mediatek/mt76/mt7615/mac.c
> > @@ -13,6 +13,11 @@
> >   #include "../dma.h"
> >   #include "mac.h"
> >   
> > +static inline s8 to_rssi(u32 field, u32 rxv)
> > +{
> > +	return (FIELD_GET(field, rxv) - 220) / 2;
> > +}
> > +
> >   static struct mt76_wcid *mt7615_rx_get_wcid(struct mt7615_dev *dev,
> >   					    u8 idx, bool unicast)
> >   {
> > @@ -120,6 +125,7 @@ int mt7615_mac_fill_rx(struct mt7615_dev *dev, struct sk_buff *skb)
> >   	if (rxd0 & MT_RXD0_NORMAL_GROUP_3) {
> >   		u32 rxdg0 = le32_to_cpu(rxd[0]);
> >   		u32 rxdg1 = le32_to_cpu(rxd[1]);
> > +		u32 rxdg3 = le32_to_cpu(rxd[3]);
> >   		u8 stbc = FIELD_GET(MT_RXV1_HT_STBC, rxdg0);
> >   		bool cck = false;
> >   
> > @@ -169,7 +175,29 @@ int mt7615_mac_fill_rx(struct mt7615_dev *dev, struct sk_buff *skb)
> >   
> >   		status->enc_flags |= RX_ENC_FLAG_STBC_MASK * stbc;
> >   
> > -		/* TODO: RSSI */
> > +		status->chains = dev->mt76.antenna_mask;
> > +		status->chain_signal[0] = to_rssi(MT_RXV4_RCPI0, rxdg3);
> > +		status->signal = status->chain_signal[0];
> > +
> > +		switch (status->chains) {
> > +		case 0x3:
> > +			status->chain_signal[1] = to_rssi(MT_RXV4_RCPI1, rxdg3);
> > +			status->signal = max(status->signal,
> > +					     status->chain_signal[1]);
> > +			break;
> > +		case 0x7:
> > +			status->chain_signal[2] = to_rssi(MT_RXV4_RCPI2, rxdg3);
> > +			status->signal = max(status->signal,
> > +					     status->chain_signal[2]);
> > +			break;
> > +		case 0xf:
> > +			status->chain_signal[3] = to_rssi(MT_RXV4_RCPI3, rxdg3);
> > +			status->signal = max(status->signal,
> > +					     status->chain_signal[3]);
> > +			break;
> > +		default:
> > +			break;
> > +		}
> >   		rxd += 6;
> >   		if ((u8 *)rxd - skb->data >= skb->len)
> >   			return -EINVAL;
> > diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mac.h b/drivers/net/wireless/mediatek/mt76/mt7615/mac.h
> > index 18ad4b8a3807..b00ce8db58e9
> > --- a/drivers/net/wireless/mediatek/mt76/mt7615/mac.h
> > +++ b/drivers/net/wireless/mediatek/mt76/mt7615/mac.h
> > @@ -98,6 +98,11 @@ enum rx_pkt_type {
> >   #define MT_RXV2_GROUP_ID		GENMASK(26, 21)
> >   #define MT_RXV2_LENGTH			GENMASK(20, 0)
> >   
> > +#define MT_RXV4_RCPI3			GENMASK(31, 24)
> > +#define MT_RXV4_RCPI2			GENMASK(23, 16)
> > +#define MT_RXV4_RCPI1			GENMASK(15, 8)
> > +#define MT_RXV4_RCPI0			GENMASK(7, 0)
> > +
> >   enum tx_header_format {
> >   	MT_HDR_FORMAT_802_3,
> >   	MT_HDR_FORMAT_CMD,
> 
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