On Thursday 30 September 2021 17:38:43 Jonas Dreßler wrote: > On 9/23/21 10:22 PM, Pali Rohár wrote: > > On Thursday 23 September 2021 22:41:30 Andy Shevchenko wrote: > > > On Thu, Sep 23, 2021 at 6:28 PM Jonas Dreßler <verdre@xxxxxxx> wrote: > > > > On 9/22/21 2:50 PM, Jonas Dreßler wrote: > > > > > > ... > > > > > > > - Just calling mwifiex_write_reg() once and then blocking until the card > > > > wakes up using my delay-loop doesn't fix the issue, it's actually > > > > writing multiple times that fixes the issue > > > > > > > > These observations sound a lot like writes (and even reads) are actually > > > > being dropped, don't they? > > > > > > It sounds like you're writing into a not ready (fully powered on) device. > > > > This reminds me a discussion with Bjorn about CRS response returned > > after firmware crash / reset when device is not ready yet: > > https://lore.kernel.org/linux-pci/20210922164803.GA203171@bhelgaas/ > > > > Could not be this similar issue? You could check it via reading > > PCI_VENDOR_ID register from config space. And if it is not valid value > > then card is not really ready yet. > > > > > To check this, try to put a busy loop for reading and check the value > > > till it gets 0. > > > > > > Something like > > > > > > unsigned int count = 1000; > > > > > > do { > > > if (mwifiex_read_reg(...) == 0) > > > break; > > > } while (--count); > > > > > > > > > -- > > > With Best Regards, > > > Andy Shevchenko > > I've tried both reading PCI_VENDOR_ID and the firmware status using a busy > loop now, but sadly none of them worked. It looks like the card always > replies with the correct values even though it sometimes won't wake up after > that. > > I do have one new observation though, although I've no clue what could be > happening here: When reading PCI_VENDOR_ID 1000 times to wakeup we can > "predict" the wakeup failure because exactly one (usually around the 20th) > of those 1000 reads will fail. What does "fail" means here? > Maybe the firmware actually tries to wake up, > encounters an error somewhere in its wakeup routines and then goes down a > special failure code path. That code path keeps the cards CPU so busy that > at some point a PCI_VENDOR_ID request times out? > > Or well, maybe the card actually wakes up fine, but we don't receive the > interrupt on our end, so many possibilities...
