Re: [PATCH] mt76: fix frag length allocation for usb

[Lorenzo Bianconi <lorenzo.bianconi@redhat.com>]

> > 
> > Hi Stanislaw,
> > 
> > I agree that we should use len in page_frag_alloc() instead of q->buf_size, so
> > 
> > Acked-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
> > 
> > but reviewing the code I guess the real issue is not q->buf_size (since it should
> > be bigger than MCU_RESP_URB_SIZE) but it is the sequence of calls in
> 
> I added printk and there are allocations where len is bigger then
> q->buf_size even with correct mt76u_alloc_queues, mt76u_mcu_init_rx
> sequence for mt76x0u:
> 
> [16426.606090] q->buf_size 2048 len 2048 nsgs 8sglen 1728
> [16426.606131] q->buf_size 2048 len 2048 nsgs 8sglen 1728
> [16426.606134] q->buf_size 2048 len 2048 nsgs 8sglen 1728
> <snip>
> [16426.606464] q->buf_size 2048 len 2048 nsgs 8sglen 1728
> [16426.607517] q->buf_size 2048 len 1024 nsgs 1sglen 1024
> [16426.939268] q->buf_size 2048 len 14584 nsgs 1sglen 14584
> [16426.984955] q->buf_size 2048 len 14584 nsgs 1sglen 14584
> 
> Not sure where it come from, but it's after MCU init (which is 1024
> third line from end).
> 
> > mt76x0u_register_device() since mt76u_alloc_queues need to be called before
> > mt76u_mcu_init_rx()
> 
> Ok, so this was already fixed in 
> 
> commit 481bb0432414f790066205fe77226b7d1877385d
> Author: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
> Date:   Wed Sep 26 13:07:39 2018 +0200
> 
>     mt76: usb: make rx page_frag_cache access atomic
> 
> but then the sequence was changed again in
> 
> commit faa605bdfaa1322ea8e85791abdb3382a8cb4e0c
> Author: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
> Date:   Fri Sep 28 13:39:00 2018 +0200
> 
>     mt76x0: usb: move initialization code in usb.c

That is an issue introduce in this commit, I am working on a fix.
Probably I got also the other reported issue. I will send a series to
test soon. Thanks.

Regards,
Lorenzo

> 
> Thanks
> Stanislaw
>