[...]
>
> My sense of humor declined quite drastically lastly ;-/
>
> > > > but we can be more cautious since probably copying
> > > > the first 128B will not make any difference
> > >
> > > Not sure if I understand what you mean.
> >
> > Please correct me if I am wrong but I think max amsdu rx size is 3839B for
> > mt76. For the sg_en case this frame will span over multiple sg buffers since
> > sg buffer size is 2048B (2 sg buffers). Moreover if we do not take into account
> > skb_shared_info when configuring the sg buffer size we will need to always copy
> > the first 128B of the first buffer since received len will be set to 2048 and
> > the following if condition will always fail:
> >
> > if (SKB_WITH_OVERHEAD(buf_size) >= MT_DMA_HDR_LEN + len) {
> > }
>
> Ok, that I understand.
>
> > > > > And skb_shered_info is needed only in first buffer IIUC.
> > > > >
> > > > > Also this patch seems to make first patch unnecessary except for
> > > > > non sg_en case (in which I think rx AMSDU is broken anyway),
> > > > > so I would prefer just to apply first patch.
> > > >
> > > > I do not think rx AMSDU is broken for non sg_en case since the max rx value
> > > > allowed should be 3839 IIRC and we alloc one page in this case
> > >
> > > If that's the case we should be fine, but then I do not understand
> > > why we allocate 8*2k buffers for sg_en case, isn't that AP can
> > > sent AMSDU frame 16k big?
> >
> > Sorry I did not get what you mean here, could you please explain?
>
> If max RX AMSDU size is 3839B I do not see reason why we allocate
> MT_SG_MAX_SIZE=8 of MT_RX_BUF_SIZE=2k buffers for sg_en case.
> I thought the reason is that max AMSDU size is 16kB so it fit into
> 8 sg buffers of 2k.
>
> In other words, for me, looks like either
> - we can not handle AMSDU for non sg case because we do not
> allocate big enough buffer
I think AMSDU is mandatory and we currently support it even for non-sg case
(since max rx AMSDU is 3839B)
> or
> - we can just use one PAGE_SIZE buffer for rx and remove sg
> buffers for rx completely
using sg buffers we can support bigger rx AMSDU size in the future without using
huge buffers (e.g. we can try to use IEEE80211_MAX_MPDU_LEN_HT_7935 with
mt76x2u)
Regards,
Lorenzo
>
> Do I miss something ?
>
> Stanislaw
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