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Subject: Re: wilc1000 driver
From:   David Mosberger-Tang <davidm@egauge.net>
To:     Nicolas Ferre <nicolas.ferre@microchip.com>,
        Ajay.Kathat@microchip.com, linux-wireless@vger.kernel.org
Cc:     Claudiu Beznea <Claudiu.Beznea@microchip.com>
Date:   Tue, 23 Feb 2021 11:09:31 -0700
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Nicolas,

On Tue, 2021-02-23 at 18:58 +0100, Nicolas Ferre wrote:
> Hi David,
> 
> On 23/02/2021 at 17:23, David Mosberger-Tang wrote:
> > OK, the problem below is caused by wilc_set_power_mgmt().  If I change
> > that function into a no-op, the driver actually works!  Does this make
> > any sense to you?  From what I saw so far, it looks like relevant code
> > is pretty much identical to the one in the linux-at91 tree and that one
> > works fine.
> 
> One thing that comes off the top of my head is that we use 
> power-sequencing drivers in the Linux4SAM trees. The use of pwrseq 
> drivers allow us to adapt the power/sequencing/delays/reset to the 
> actual board the wilc1000 but moreover the wilc3000 is soldered to.
> Indeed the wilc3000 needs special sequence to be up'n running if some 
> clock signals are connected to the SoC output for instance.
> 
> You can have an example of a pwrseq driver here:
> drivers/mmc/core/pwrseq_wilc.c
> (https://github.com/linux4sam/linux-at91/blob/master/drivers/mmc/core/pwrseq_wilc.c). 
> There are other pwrseq drivers for other WiFi chips and boards there.
> 
> True thing is that this sequencing seems dedicated to mmc sub-system and 
> I don't know if it can be used for SPI-based WiFi connections or if 
> another mechanism exists.

Ah, *that's* where the RESET pins are hiding.  Yeah, it wouldn't have
occurred to me to like in the MMC subsystem, but I see there is a
precedent for another WiFi chip using that place.  OK, I things are
starting to make sense and I should be able to work on the actual
patches I've been meaning to submit.

Thanks for the help!

  --david