[PATCH] wifi: mt76: mt7921e: Perform FLR to recovery the device

[Deren Wu (武德仁)]

On Wed, 2023-06-14 at 13:18 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Il 14/06/23 08:32, Kai-Heng Feng ha scritto:
> > When "Pre-boot WiFi" is enabled in BIOS, the mt7921e device may not
> > work:
> > mt7921e 0000:02:00.0: ASIC revision: 79220010
> > mt7921e 0000:02:00.0: Message 00000010 (seq 1) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 2) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 3) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 4) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 5) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 6) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 7) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 8) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 9) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: Message 00000010 (seq 10) timeout
> > mt7921e 0000:02:00.0: Failed to get patch semaphore
> > mt7921e 0000:02:00.0: hardware init failed
> > 
> > After some trials and errors, it shows that PCI function level
> reset can
> > recover the device back to a functional state.
> > 
> > So perform FLR at probe routine to workaround the issue.
> 
> Is there any way to check if the device was enabled before booting
> Linux?
> 
> I'm thinking of something like
> 
> if (device_is_already_enabled)
> ret = pci_reset_function_locked(....)
> 
> Regards,
> Angelo

Hi Kai-Heng,

Thanks for the patch. But we found there are some problems on different
platform. We will provide another solution for this case.


Hi Angelo,

Because the problem is caused by mt7912e enabled and some status was
changed to an unpreditable value durgin boot process, we may have to
force reset devices in probe(). We still try to find out a good way to
do it and will post the patch once the verification is done.


Regards,
Deren

> 
> > 
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
> > ---
> >   drivers/net/wireless/mediatek/mt76/mt7921/pci.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> > index ddb1fa4ee01d..9671fbe35a8e 100644
> > --- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> > +++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> > @@ -262,6 +262,10 @@ static int mt7921_pci_probe(struct pci_dev
> *pdev,
> >   int ret;
> >   u16 cmd;
> >   
> > +ret = pci_reset_function_locked(pdev);
> > +if (ret)
> > +pci_info(pdev, "Unable to perform FLR\n");
> > +
> >   ret = pcim_enable_device(pdev);
> >   if (ret)
> >   return ret;
> 
>