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From: Krishna Chaitanya <chaitanya.mgit@gmail.com>
Date: Sat, 9 Nov 2013 02:00:43 +0530
Message-ID: <CABPxzYJsLqJbJQzr8+2GujQsbJpo922v9ouVWWPbTFL11-UV5g@mail.gmail.com> (sfid-20131108_213111_292136_0CF310C6)
Subject: Re: I always need a miracle to connect with iwlwifi
To: Felipe Contreras <felipe.contreras@gmail.com>
Cc: Oleksij Rempel <linux@rempel-privat.de>, ilw@linux.intel.com,
	"hostap@lists.shmoo.com" <hostap@lists.shmoo.com>,
	linux-wireless Mailing List <linux-wireless@vger.kernel.org>
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On Fri, Nov 8, 2013 at 7:48 PM, Felipe Contreras
<felipe.contreras@gmail.com> wrote:
> On Fri, Nov 8, 2013 at 8:06 AM, Krishna Chaitanya
> <chaitanya.mgit@gmail.com> wrote:
>> On Fri, Nov 8, 2013 at 6:44 PM, Felipe Contreras
>> <felipe.contreras@gmail.com> wrote:
>>> On Fri, Nov 8, 2013 at 2:35 AM, Felipe Contreras
>>> <felipe.contreras@gmail.com> wrote:
>>>> On Sat, Nov 2, 2013 at 2:05 PM, Krishna Chaitanya
>>>> <chaitanya.mgit@gmail.com> wrote:
>>>>
>>>>> Also one more thing you said N900 uses mac80211 and it has no issues, but as
>>>>> its a embedded device it might running an older kernel where the
>>>>> handling might be
>>>>> different, so we need to try with the same kernel you are facing an
>>>>> issue with the
>>>>> a driver which advertises IEEE80211_HW_NEED_DTIM_BEFORE_ASSOC.
>>>>
>>>> Yes it was running an older kernel, but I just compiled v3.12 and ran
>>>> it on the N900, and still everything works fine.
>>>>
>>>>> (or) if you a have a compilation environment try commenting the advertisement of
>>>>> IEEE80211_HW_NEED_DTIM_BEFORE_ASSOC in the iwlwifi DVM driver and
>>>>> try to reproduce the issue.
>>>>
>>>> After commenting that flag everything works fine :)
>>
>> Oh, great. That was just to corner the problem, that means we are not getting
>> the required beacon  before the association, but we only wait for 1 beacon here
>> may be we to wait for some number of beacons before giving up the association??
>>
>> Johannes??
>
> But we are receiving 0 beacons, waiting for more than 1 won't help.
> BTW, why NEED_DTIM_BEFORE_ASSOC if the device doesn't *need* the DTIM
> before the association?
>
>>>> What are the next steps?
>>>
>>> I tried to add some debugging to see what's going on, and indeed the
>>> beacon packets are lost, I added debugging as low in the chain as I
>>> could (iwlagn_rx_reply_rx()), and I don't see them there. However,
>>> when I enable the monitor mode, I see them. What's going on?
>>
>> In the captures you shared all the beacons are malformed, so
>> probably they failed the CRC check. iwlwifi drops all the CRC failed
>> packets. (doth MVM and DVM)
>
> Before iwlagn_rx_reply_rx()?
>
>> Not sure how you are receiving the beacons in the monitor mode.
>
> I don't know what kismet does, but I can see my debugging is printing them.
>
>> BTW did you tried capturing the beacons in other devices and see if they
>> are really malformed, or is it just iwlwifi interpreting them wrongly.?
>
> I haven't managed to do that yet.
>
> This is what I'm doing:
>
> --- a/drivers/net/wireless/iwlwifi/dvm/rx.c
> +++ b/drivers/net/wireless/iwlwifi/dvm/rx.c
> @@ -919,6 +919,11 @@ static int iwlagn_rx_reply_rx(struct iwl_priv *priv,
>         ampdu_status = iwlagn_translate_rx_status(priv,
>                                                   le32_to_cpu(rx_pkt_status));
>
> +       if (ieee80211_is_beacon(header->frame_control)) {
> +               print_hex_dump(KERN_INFO, "iwlwifi: dump: ", DUMP_PREFIX_OFFSET,
> +                               16, 1, header, len, true);
> +       }
> +
>         if ((unlikely(phy_res->cfg_phy_cnt > 20))) {
>                 IWL_DEBUG_DROP(priv, "dsp size out of range [0,20]: %d\n",
>                                 phy_res->cfg_phy_cnt);
>
Oops...you just missed, Right after your print there is a check to
drop frames with BAD CRC :-).
Line 928.

    ampdu_status = iwlagn_translate_rx_status(priv,
                          le32_to_cpu(rx_pkt_status));

    if ((unlikely(phy_res->cfg_phy_cnt > 20))) {
        IWL_DEBUG_DROP(priv, "dsp size out of range [0,20]: %d\n",
                phy_res->cfg_phy_cnt);
        return 0;
    }

    if (!(rx_pkt_status & RX_RES_STATUS_NO_CRC32_ERROR) ||
        !(rx_pkt_status & RX_RES_STATUS_NO_RXE_OVERFLOW)) {
        IWL_DEBUG_RX(priv, "Bad CRC or FIFO: 0x%08X.\n",
                le32_to_cpu(rx_pkt_status));
        return 0;
    }