Date:   Mon, 11 Mar 2019 15:58:52 +0100
From:   Stanislaw Gruszka <sgruszka@redhat.com>
To:     Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc:     Lorenzo Bianconi <lorenzo@kernel.org>, nbd@nbd.name,
        ryder.lee@mediatek.com, roychl666@gmail.com,
        linux-wireless@vger.kernel.org
Subject: Re: [PATCH 2/4] mt76: mmio: move mt76_insert_hdr_pad in
 mt76_dma_tx_queue_skb
Message-ID: <20190311145852.GF6089@redhat.com>
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On Mon, Mar 11, 2019 at 03:25:18PM +0100, Lorenzo Bianconi wrote:
> On Mar 11, Stanislaw Gruszka wrote:
> > On Mon, Mar 11, 2019 at 01:35:24PM +0100, Lorenzo Bianconi wrote:
> > > Introduce tx_aligned4_skbs in mt76_driver_ops and move
> > > mt76_insert_hdr_pad in mt76_dma_tx_queue_skb. This is a preliminary
> > > patch in order to unify tx dma mapping for mt76x02 and new chipsets
> > > 
> > > Signed-off-by: Felix Fietkau <nbd@nbd.name>
> > > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > > ---
> > >  drivers/net/wireless/mediatek/mt76/dma.c          |  3 +++
> > >  drivers/net/wireless/mediatek/mt76/mt76.h         |  1 +
> > >  drivers/net/wireless/mediatek/mt76/mt76x0/pci.c   |  1 +
> > >  drivers/net/wireless/mediatek/mt76/mt76x02_txrx.c | 13 +++++--------
> > >  drivers/net/wireless/mediatek/mt76/mt76x2/pci.c   |  1 +
> > >  5 files changed, 11 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
> > > index a66832a02281..14dd6585bab4 100644
> > > --- a/drivers/net/wireless/mediatek/mt76/dma.c
> > > +++ b/drivers/net/wireless/mediatek/mt76/dma.c
> > > @@ -300,6 +300,9 @@ mt76_dma_tx_queue_skb(struct mt76_dev *dev, enum mt76_txq_id qid,
> > >  	}
> > >  
> > >  	skb->prev = skb->next = NULL;
> > > +	if (dev->drv->tx_aligned4_skbs)
> > > +		mt76_insert_hdr_pad(skb);
> > 
> > We need 4 bytes aligned skbs for mt76x02 or we just need header
> > lenght be multiple of 4 ?  
> 
> I think IV/LLC should be 4 byte aligned

mt76_insert_hdr_pad() does not change alignment of IV/LLC , it only
moves header.

I'm not sure what is actually needed (4 bytes alignment or 4 bytes
lenght), but I just saw Felix sent 2 mac80211 patches that hopfully
do the right thing, so this code after appling mac80211 changes
and set TX_NEEDS_ALIGNED4_SKBS can be removed.

Stanislaw