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From: Bjorn Helgaas <bhelgaas@google.com>
Date: Thu, 14 Sep 2017 12:11:28 -0500
Message-ID: <CAErSpo777jq9FVRtmoHXVbzE-ZOc7mnT+eRJ_PhP_Dd=MbKv4g@mail.gmail.com> (sfid-20170914_191153_279103_A9A5B812)
Subject: Re: iwlwifi firmware load broken in current -git
To: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Berg <johannes@sipsolutions.net>,
        Luca Coelho <luca@coelho.fi>,
        "Grumbach, Emmanuel" <emmanuel.grumbach@intel.com>,
        linuxwifi <linuxwifi@intel.com>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        srinath.mannam@broadcom.com,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
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Sender: linux-wireless-owner@vger.kernel.org

[+cc linux-pci]

On Thu, Sep 14, 2017 at 12:00 PM, Jens Axboe <axboe@kernel.dk> wrote:
> On 09/12/2017 02:04 PM, Johannes Berg wrote:
>> On Tue, 2017-09-12 at 13:43 -0600, Jens Axboe wrote:
>>
>>> CC'ing the guilty part and Bjorn. I'm assuming it's the
>>> pci_is_enabled() check, since the rest of the patch shouldn't have
>>> functional changes.
>>
>> and pci_enable_bridge() already checks if it's already enabled, but
>> still enables mastering in that case if it isn't:
>>
>> static void pci_enable_bridge(struct pci_dev *dev)
>> {
>> [...]
>>         if (pci_is_enabled(dev)) {
>>                 if (!dev->is_busmaster)
>>                         pci_set_master(dev);
>>                 return;
>>         }
>>
>> so I guess due to the new check we end up with mastering disabled, and
>> thus the firmware can't load since that's a DMA thing?
>
> Bjorn/Srinath, any input here? This is a regression that prevents wifi
> from working on a pretty standard laptop. It'd suck to have this be in
> -rc1. Seems like the trivial fix would be:
>
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b0002daa50f3..ffbe11dbdd61 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1394,7 +1394,7 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
>                 return 0;               /* already enabled */
>
>         bridge = pci_upstream_bridge(dev);
> -       if (bridge && !pci_is_enabled(bridge))
> +       if (bridge)
>                 pci_enable_bridge(bridge);
>
>         /* only skip sriov related */
>
>

Looks like a reasonable fix.  I assume it works for you?  I don't have
a way to test it, so if you can verify that it works and supply a
Signed-off-by, I can merge it.

Bjorn