[PATCH v2] ath10k: Retry pci probe on failure.

[Adrian Chadd]

On 13 October 2017 at 05:41, Kalle Valo <kvalo at qca.qualcomm.com> wrote:
> greearb at candelatech.com writes:
>
>> From: Ben Greear <greearb at candelatech.com>
>>
>> This works around a problem we see when sometimes the wifi NIC does
>> not respond the first time.  This seems to happen especially often on
>> some of the 9984 NICs in mid-range platforms.
>>
>> Signed-off-by: Ben Greear <greearb at candelatech.com>
>
> [...]
>
>> -static int ath10k_pci_probe(struct pci_dev *pdev,
>> -                         const struct pci_device_id *pci_dev)
>> +static int __ath10k_pci_probe(struct pci_dev *pdev,
>> +                           const struct pci_device_id *pci_dev)
>>  {
>>       int ret = 0;
>>       struct ath10k *ar;
>> @@ -3672,6 +3672,22 @@ static int ath10k_pci_probe(struct pci_dev *pdev,
>>       return ret;
>>  }
>>
>> +static int ath10k_pci_probe(struct pci_dev *pdev,
>> +                         const struct pci_device_id *pci_dev)
>> +{
>> +     int cnt = 0;
>> +     int rv;
>> +     do {
>> +             rv = __ath10k_pci_probe(pdev, pci_dev);
>> +             if (rv == 0)
>> +                     return rv;
>> +             pr_err("ath10k: failed to probe PCI : %d, retry-count: %d\n", rv, cnt);
>> +             mdelay(10); /* let the ath10k firmware gerbil take a small break */
>> +     } while (cnt++ < 10);
>> +     return rv;
>> +}
>
> This is a sledgehammer approach and it causes reload for all error
> cases, like when hardware is broken or memory allocation is failing.
>
> When the problem happens does it always fail at the the same place? Is
> it hw reset or something else? It's better to retry the invidiual action
> than to do this hack. Or is it just some more delay needed somewhere?

I am seeing WMI timeouts during initial firmware load and wait on
QCA9984 + BCM7444S SoC.
My guess is the WMI wakeup time is not "right" enough and needs to be
extended a little bit.

But then, I have played a lot of whackamole with WMI timeouts during
my loooong porting effort..


-adrian