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From:   Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Date:   Wed, 21 Dec 2022 21:46:15 +0500
Message-ID: <CABXGCsNJKy2SQffeU+uaua5SM_77YiGKdPLRdzSF3F+ShpF+5w@mail.gmail.com>
Subject: Re: [6.2][regression] after commit cd372b8c99c5a5cf6a464acebb7e4a79af7ec8ae
 stopping working wifi mt7921e
To:     Felix Fietkau <nbd@nbd.name>
Cc:     lorenzo@kernel.org, sujuan.chen@mediatek.com,
        Linux List Kernel Mailing <linux-wireless@vger.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
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On Wed, Dec 21, 2022 at 7:12 PM Felix Fietkau <nbd@nbd.name> wrote:
>
> Thanks! I guess I focused on the wrong part of your kernel log
> initially. After more code review, I found that there is in fact a DMA
> related bug in the commit that your bisection pointed to, which happened
> to uncover and trigger the deadlock fixed by my other patch.
>
> So here's my fix for the DMA issue:
> ---
[cutted]
>                 qbuf.skip_unmap = false;
> -               if (mt76_dma_add_buf(dev, q, &qbuf, 1, 0, buf, t) < 0) {
> +               if (mt76_dma_add_rx_buf(dev, q, &qbuf, buf) < 0) {
>                         dma_unmap_single(dev->dma_dev, addr, len,
>                                          DMA_FROM_DEVICE);
>                         skb_free_frag(buf);
>

Sorry for stupid question.

Do you have a separate branch?
I see that the code is differ between master branch and the patch.

For example in patch the line:
- if (mt76_dma_add_buf(dev, q, &qbuf, 1, 0, buf, t) < 0) {
replaced by the line:
+ if (mt76_dma_add_rx_buf(dev, q, &qbuf, buf) < 0) {

But in master branch
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/mediatek/mt76/dma.c?id=b6bb9676f2165d518b35ba3bea5f1fcfc0d969bf#n604
after line:
qbuf.skip_unmap = false;
followed the line:
mt76_dma_add_buf(dev, q, &qbuf, 1, 0, buf, t);
without if condition.

So I'm stuck applying the patch :(

-- 
Best Regards,
Mike Gavrilov.