linux-kernel - Re: [PATCH] wifi: rtw88: sdio: Honor the host max_req

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Message-ID: <CAFBinCDRWJGr1F0vLj_=k7TYQmGOQRWS=3n1DDQwpxr5AYtt9Q@mail.gmail.com>
Date:   Wed, 26 Jul 2023 19:37:39 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Ping-Ke Shih <pkshih@...ltek.com>
Cc:     "Lukas F. Hartmann" <lukas@...re.com>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jernej.skrabec@...il.com" <jernej.skrabec@...il.com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "kvalo@...nel.org" <kvalo@...nel.org>,
        "tony0620emma@...il.com" <tony0620emma@...il.com>
Subject: Re: [PATCH] wifi: rtw88: sdio: Honor the host max_req_size in the RX path

Hello Ping-Ke,

On Fri, Jul 14, 2023 at 2:34 AM Ping-Ke Shih <pkshih@...ltek.com> wrote:
[...]
> > Here are the errors that lead up to this:
> > http://dump.mntmn.com/rtw88-failure-1h-dmesg.txt
>
> Hi Martin,
>
> The dmesg shows that
> "rtw_8822cs mmc2:0001:1: Failed to read 1536 byte(s) from SDIO port 0x000000d1"
>
> Shouldn't we return an error code (with proper error handling) instead of
> just break the loop? Because 'buf' content isn't usable.
In my opinion we are properly breaking the loop:
"ret" will be non-zero so the error code is returned from
rtw_sdio_read_port() to the caller.
The (only) caller is rtw_sdio_rxfifo_recv() which sees the non-zero
return code and aborts processing.
What do you think?

> I wonder the approach of this patch is still not enough for Lukas' platform.
On IRC Lukas wrote:
  funny, i can reproduce skb_panic when opening this page in chromium
https://embedded.avnet.com/product/msc-sm2s-ryz/
and:
  still getting spurious skb_panics, even after disabling rx aggregation.

I haven't had the time to look into this any further yet.
Unfortunately I also don't have any hardware to reproduce this problem
either, which unfortunately results in this long ping-pong.
Lukas, could you please add two more prints:
- in the rtw_warn with "Failed to read %zu byte(s) from SDIO port":
please also print the ret variable (with %d) - I'm curious what the
reported error is (it could be some CRC error which would mean ret is
-EILSEQ)
- add something like the following at the end of rtw_sdio_read_port()
(right before "return ret"):

if (!ret && count > 1000) {
    printk(KERN_INFO "rtw_sdio_read_port() with %zu bytes:", count);
    print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 1, buf, count, false);
}

(note: I only compile-tested this)
The very last output of this (potentially spammy) output will contain
the full buffer that's causing the problem.


Best regards,
Martin