Re: [PATCH v6 2/5] mt76: mt76x02: split beaconing

[Stanislaw Gruszka <sgruszka@redhat.com>]

On Tue, Nov 19, 2019 at 04:47:43PM +0100, Markus Theil wrote:
> Sending beacons to the hardware always happens in batches. In order to
> speed up beacon processing on usb devices, this patch splits out common
> code an calls it only once (mt76x02_mac_set_beacon_prepare,
> mt76x02_mac_set_beacon_finish). Making this split breaks beacon
> enabling/disabling per vif. This is fixed by adding a call to set the
> bypass mask, if beaconing should be disabled for a vif. Otherwise the
> beacon is send after the next beacon interval.
> 
> The code is also adapted for the mmio part of the driver, but should not
> have any performance implication there.
> 
> Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
> ---
>  .../wireless/mediatek/mt76/mt76x02_beacon.c   | 44 +++++++------------
>  .../net/wireless/mediatek/mt76/mt76x02_mac.h  |  1 +
>  .../net/wireless/mediatek/mt76/mt76x02_mmio.c |  5 +++
>  .../wireless/mediatek/mt76/mt76x02_usb_core.c |  5 +++
>  4 files changed, 26 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c b/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
> index 403866496640..09013adae854 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_beacon.c
> @@ -47,10 +47,6 @@ __mt76x02_mac_set_beacon(struct mt76x02_dev *dev, u8 bcn_idx,
>  	int beacon_len = dev->beacon_ops->slot_size;
>  	int beacon_addr = MT_BEACON_BASE + (beacon_len * bcn_idx);
>  	int ret = 0;
> -	int i;
> -
> -	/* Prevent corrupt transmissions during update */
> -	mt76_set(dev, MT_BCN_BYPASS_MASK, BIT(bcn_idx));
>  
>  	if (skb) {
>  		ret = mt76x02_write_beacon(dev, beacon_addr, skb);
> @@ -60,41 +56,30 @@ __mt76x02_mac_set_beacon(struct mt76x02_dev *dev, u8 bcn_idx,
>  		dev->beacon_data_mask &= ~BIT(bcn_idx);
>  	}
>  
> -	mt76_wr(dev, MT_BCN_BYPASS_MASK, 0xff00 | ~dev->beacon_data_mask);
> -
>  	return ret;
>  }
>  
> -int mt76x02_mac_set_beacon(struct mt76x02_dev *dev, u8 vif_idx,
> -			   struct sk_buff *skb)
> +void mt76x02_mac_set_beacon_finish(struct mt76x02_dev *dev)
>  {
> -	bool force_update = false;
> -	int bcn_idx = 0;
>  	int i;
> +	int bcn_idx = 0;
>  
> -	for (i = 0; i < ARRAY_SIZE(dev->beacons); i++) {
> -		if (vif_idx == i) {
> -			force_update = !!dev->beacons[i] ^ !!skb;
> -			dev_kfree_skb(dev->beacons[i]);
> -			dev->beacons[i] = skb;
> -			__mt76x02_mac_set_beacon(dev, bcn_idx, skb);
> -		} else if (force_update && dev->beacons[i]) {
> -			__mt76x02_mac_set_beacon(dev, bcn_idx,
> -						 dev->beacons[i]);
> -		}
> -
> +	for (i = 0; i < hweight8(dev->mt76.beacon_mask); ++i)
>  		bcn_idx += !!dev->beacons[i];

This looks wrong since we do not calculate all beacons, only 
up to hweight8(dev->mt76.beacon_mask).

But since we need to calculate number of all beacons we can just
use hweight8(dev->mt76.beacon_mask) directly.

> -	}
> -
> -	for (i = bcn_idx; i < ARRAY_SIZE(dev->beacons); i++) {
> -		if (!(dev->beacon_data_mask & BIT(i)))
> -			break;
> -
> -		__mt76x02_mac_set_beacon(dev, i, NULL);
> -	}
>  
>  	mt76_rmw_field(dev, MT_MAC_BSSID_DW1, MT_MAC_BSSID_DW1_MBEACON_N,
>  		       bcn_idx - 1);
> +
> +	mt76_wr(dev, MT_BCN_BYPASS_MASK, 0xff00 | ~dev->beacon_data_mask);

I'm not sure if this is correct for multi bss.

In MT7620 manual BCM_BAYPASS_MASK is described as below:

"
Directly bypasses the Tx Beacon frame with the  specified 
Beacon number. Bit0=Nth Beacon, bit1=(N- 1)th Beacon,... etc.
N is the number of  Beacons defined in the  MULTI_BCN_NUM field in the 
MAC_BSSID_DW1(offset: 0x1014) register.
0: Disable
1: Enable
"

Assuming manual is correct (it could be wrong) bypass mask should be
calculated differently.

Stanislaw