linux-kernel - Re: [PATCH v2 2/2] mwifiex: pcie: add reset_d3cold quirk for Surface gen4+ devices

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Date:   Sat, 10 Jul 2021 02:07:56 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Maximilian Luz <luzmaximilian@...il.com>
Cc:     Jonas Dreßler <verdre@...d.nl>,
        Amitkumar Karwar <amitkarwar@...il.com>,
        Xinming Hu <huxinming820@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Tsuchiya Yuto <kitakar@...il.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v2 2/2] mwifiex: pcie: add reset_d3cold quirk for Surface
 gen4+ devices

On Saturday 10 July 2021 02:00:08 Maximilian Luz wrote:
> On 7/10/21 12:54 AM, Pali Rohár wrote:
> 
> [...]
> 
> > > Also not sure if this is just my bias, but it feels like the Surface
> > > line always had more problems with that driver (and firmware) than
> > > others.
> > 
> > Ehm, really? I see reports also from non-Surface users about bad quality
> > of these 88W[89]xxx cards and repeating firmware issues. I have bad
> > personal experience with 88W8997 SDIO firmware and lot of times I get
> > advice about ex-Marvell/NXP wifi cards "do not touch and run away
> > quickly".
> 
> Yeah, then I'm probably biased since I'm mostly dealing with Surface
> stuff.
> 
> > I think that more people if they get mPCIe/M.2 wifi card in laptop which
> > does not work, they just replace it with some working one. And not
> > spending infinite time in trying to fix it... So this may explain why
> > there are more Surface users with these issues...
> 
> That might be an explanation. If it wouldn't need a heat-gun to open it
> up, I'd probably have done that at some point in the past (there were
> times when WiFi at my Uni was pretty much unusable with this device...
> and I'm still not sure what fixed that or even if it's fixed completely).
> 
> > > I'm honestly a bit surprised that MS stuck with them for this
> > > long (they decided to go with Intel for 7th gen devices). AFAICT they
> > > initially chose Marvell due to connected standby support, so maybe that
> > > causes issue for us and others simply aren't using that feature? Just
> > > guessing though.
> > 
> > In my opinion that "Connected Standby" is just MS marketing term.
> 
> I can only really repeat what I've been told: Apparently when they
> started designing those devices, the only option with "Connected
> standby" (or probably rather that feature set that MS wanted) was,
> unfortunately for us, Marvell.
> 
> > 88W[89]xxx chips using full-mac firmware and drivers [*]. Full-mac lot
> > of times causing more issues than soft-mac solution. Moreover this
> > Marvell firmware implements also other "application" layers in firmware
> > which OS drivers can use, e.g. there is fully working "wpa-supplicant"
> > replacement and also AP part. Maybe windows drivers are using it and it
> > cause less problems? Duno. mwifiex uses only "low level" commands and
> > WPA state machine is implemented in userspace wpa-supplicant daemon.
> > 
> > [*] - Small note: There are also soft-mac firmwares and drivers but
> > apparently Marvell has never finished linux driver and firmware was not
> > released to public...
> > 
> > And there is also Laird Connectivity which offers their own proprietary
> > linux kernel drivers with their own firmware for these 88W[89]xxx chips.
> > Last time I checked it they released some parts of driver on github.
> > Maybe somebody could contact Laird or check if their driver can be
> > replaced by mwifiex? Or just replacing ex-Marvell/NXP firmware by their?
> > But I'm not sure if they have something for 88W8897.
> 
> Interesting, I was not aware of this. IIRC we've been experimenting with
> the mwlwifi driver (which that lrdmwl driver seems to be based on?), but
> couldn't get that to work with the firmware we have.

mwlwifi is that soft-mac driver and uses completely different firmware.
For sure it would not work with current full-mac firmware.

> IIRC it also didn't
> work with the Windows firmware (which seems to be significantly
> different from the one we have for Linux and seems to use or be modeled
> after some special Windows WiFi driver interface).

So... Microsoft has different firmware for this chip? And it is working
with mwifiex driver?