netdev - Re: [PATCH RESEND] wifi: mt76: mt7921e: Set memory space enable in PCI

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Date:   Sun, 9 Apr 2023 20:04:43 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     "lorenzo@...nel.org" <lorenzo@...nel.org>,
        "ryder.lee@...iatek.com" <ryder.lee@...iatek.com>,
        "nbd@....name" <nbd@....name>
Cc:     "shayne.chen@...iatek.com" <shayne.chen@...iatek.com>,
        "sean.wang@...iatek.com" <sean.wang@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "Tsao, Anson" <anson.tsao@....com>, Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Sean Wang <sean.wang@...nel.org>
Subject: Re: [PATCH RESEND] wifi: mt76: mt7921e: Set memory space enable in
 PCI_COMMAND if unset


On 4/9/23 19:57, Sean Wang wrote:
> On Mon, Apr 3, 2023 at 6:42 AM Limonciello, Mario
> <Mario.Limonciello@....com> wrote:
>> [Public]
>>
>>> On 3/29/2023 18:24, Sean Wang wrote:
>>>> Hi,
>>>>
>>>> On Wed, Mar 29, 2023 at 1:18 PM Mario Limonciello
>>>> <mario.limonciello@....com> wrote:
>>>>> When the BIOS has been configured for Fast Boot, systems with mt7921e
>>>>> have non-functional wifi.  Turning on Fast boot caused both bus master
>>>>> enable and memory space enable bits in PCI_COMMAND not to get
>>> configured.
>>>>> The mt7921 driver already sets bus master enable, but explicitly check
>>>>> and set memory access enable as well to fix this problem.
>>>>>
>>>>> Tested-by: Anson Tsao <anson.tsao@....com>
>>>>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>>>>> ---
>>>>> Original patch was submitted ~3 weeks ago with no comments.
>>>>> Link: https://lore.kernel.org/all/20230310170002.200-1-
>>> mario.limonciello@....com/
>>>>> ---
>>>>>    drivers/net/wireless/mediatek/mt76/mt7921/pci.c | 6 ++++++
>>>>>    1 file changed, 6 insertions(+)
>>>>>
>>>>> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
>>> b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
>>>>> index cb72ded37256..aa1a427b16c2 100644
>>>>> --- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
>>>>> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
>>>>> @@ -263,6 +263,7 @@ static int mt7921_pci_probe(struct pci_dev *pdev,
>>>>>           struct mt76_dev *mdev;
>>>>>           u8 features;
>>>>>           int ret;
>>>>> +       u16 cmd;
>>>>>
>>>>>           ret = pcim_enable_device(pdev);
>>>>>           if (ret)
>>>>> @@ -272,6 +273,11 @@ static int mt7921_pci_probe(struct pci_dev
>>> *pdev,
>>>>>           if (ret)
>>>>>                   return ret;
>>>>>
>>>>> +       pci_read_config_word(pdev, PCI_COMMAND, &cmd);
>>>>> +       if (!(cmd & PCI_COMMAND_MEMORY)) {
>>>>> +               cmd |= PCI_COMMAND_MEMORY;
>>>>> +               pci_write_config_word(pdev, PCI_COMMAND, cmd);
>>>>> +       }
>>>> If PCI_COMMAND_MEMORY is required in any circumstance, then we
>>> don't
>>>> need to add a conditional check and OR it with PCI_COMMAND_MEMORY.
>>> Generally it seemed advantageous to avoid an extra PCI write if it's not
>>> needed.  For example that's how bus mastering works too (see
>>> __pci_set_master).
>>>
>>>
>>>> Also, I will try the patch on another Intel machine to see if it worked.
>>> Thanks.
>> Did you get a chance to try this on an Intel system?
> Hi,
>
> Sorry for the late response. We have tested the related Intel platform
> and it worked fine. You can add the tag from me like
> Acked-by: Sean Wang <sean.wang@...iatek.com>
>
Thanks!

Felix, Lorenzo, or Ryder can you guys please pick this up?

Thanks,