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From: AceLan Kao <acelan.kao@canonical.com>
Date: Thu, 5 Oct 2017 14:39:12 +0800
Message-ID: <CAFv23QkLJ0m112Y8iAGv+6DyFT52Hqnxq5Fy=ryWTWxu8oTXdw@mail.gmail.com> (sfid-20171005_083932_362588_8564362F)
Subject: Re: [PATCH 2/6] ath9k: add a quirk to set use_msi automatically
To: Daniel Drake <drake@endlessm.com>
Cc: Kalle Valo <kvalo@codeaurora.org>,
        Christoph Hellwig <hch@infradead.org>,
        QCA ath9k Development <ath9k-devel@qca.qualcomm.com>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        "Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>
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Sender: linux-wireless-owner@vger.kernel.org

Hi all,

Please drop my patches, Qualcomm is working internally and will submit
the MSI patch by themselves.
Thanks.

Hi Daniel,

I'll try your patches tomorrow.

Best regards,
AceLan Kao.

2017-10-02 12:21 GMT+08:00 Daniel Drake <drake@endlessm.com>:
> Hi AceLan,
>
> On Thu, Sep 28, 2017 at 4:28 PM, AceLan Kao <acelan.kao@canonical.com> wrote:
>> Hi Daniel,
>>
>> I've tried your patch, but it doesn't work for me.
>> Wifi can scan AP, but can't get connected.
>
> Can you please clarify which patch(es) you have tried?
>
> This is the base patch which adds the infrastructure to request
> specific MSI IRQ vectors:
> https://marc.info/?l=linux-wireless&m=150631274108016&w=2
>
> This is the ath9k MSI patch which makes use of that:
> https://github.com/endlessm/linux/commit/739c7a924db8f4434a9617657
>
> If you were already able to use ath9k MSI interrupts without specific
> consideration for which MSI vector numbers were used, these are the
> possible explanations that spring to mind:
>
> 1. You got lucky and it picked a vector number that is 4-aligned. You
> can check this in the "lspci -vvv" output. You'll see something like:
> Capabilities: [50] MSI: Enable+ Count=1/4 Maskable+ 64bit+
>         Address: 00000000fee0300c  Data: 4142
> The lower number is the vector number. In my example here 0x42 (66) is
> not 4-aligned so the failure condition will be hit.
>
> 2. You are using interrupt remapping, which I suspect may provide a
> high likelihood of MSI interrupt vectors being 4-aligned. See if
> /proc/interrupts shows the IRQ type as IR-PCI-MSI
> Unfortunately interrupt remapping is not available here,
> https://lists.linuxfoundation.org/pipermail/iommu/2017-August/023717.html
>
> 3. My assumption that all ath9k hardware corrupts the MSI vector
> number could wrong. However we've seen this on different wifi modules
> in laptops produced by different OEMs and ODMs, so it seems to be a
> somewhat widespread problem at least.
>
> 4. My assumption that ath9k hardware is corrupting the MSI vector
> number could be wrong; maybe another component is to blame, could it
> be a BIOS issue? Admittedly I don't really know how I can debug the
> layers inbetween seeing the MSI Message Data value disagree with the
> vector number being handled inside do_IRQ().
>
> Daniel