Subject: Re: [PATCH] Revert "wlcore: Adding suppoprt for IGTK key in wlcore driver"

From: Mauro Carvalho Chehab <[email-masked]>
Date: Thu, 27 Aug 2020 19:42:25 +0200

Em Thu, 27 Aug 2020 08:48:30 -0700
Steve deRosier <[email-masked]> escreveu:

> On Tue, Aug 25, 2020 at 10:49 PM Mauro Carvalho Chehab
> <[email-masked]> wrote:
> >
> > This patch causes a regression betwen Kernel 5.7 and 5.8 at wlcore:
> > with it applied, WiFi stops working, and the Kernel starts printing
> > this message every second:
> >
> >    wlcore: PHY firmware version: Rev 8.2.0.0.242
> >    wlcore: firmware booted (Rev 8.9.0.0.79)
> >    wlcore: ERROR command execute failure 14  
> 
> Only if NO firmware for the device in question supports the `KEY_IGTK`
> value, then this revert is appropriate. Otherwise, it likely isn't.

Yeah, that's what I suspect too: some specific firmware is required
for KEY_IGTK to work.

>  My suspicion is that the feature that `KEY_IGTK` is enabling is
> specific to a newer firmware that Mauro hasn't upgraded to. What the
> OP should do is find the updated firmware and give it a try.

I didn't try checking if linux-firmware tree has a newer version on
it. I'm using Debian Bullseye on this device. So, I suspect that
it may have a relatively new firmware.

Btw, that's also the version that came together with Fedora 32:

	$ strings /lib/firmware/ti-connectivity/wl18xx-fw-4.bin |grep FRev
	FRev 8.9.0.0.79
	FRev 8.2.0.0.242

Looking at:
	https://git.ti.com/cgit/wilink8-wlan/wl18xx_fw/

It sounds that there's a newer version released this year:

	2020-05-28	Updated to FW 8.9.0.0.81
	2018-07-29	Updated to FW 8.9.0.0.79

However, it doesn't reached linux-firmware upstream yet:

	$ git log --pretty=oneline ti-connectivity/wl18xx-fw-4.bin
	3a5103fc3c29 wl18xx: update firmware file 8.9.0.0.79
	65b1c68c63f9 wl18xx: update firmware file 8.9.0.0.76
	dbb85a5154a5 wl18xx: update firmware file
	69a250dd556b wl18xx: update firmware file
	dbe3f134bb69 wl18xx: update firmware file, remove conf file
	dab4b79b3fbc wl18xx: add version 4 of the wl18xx firmware

> AND - since there's some firmware the feature doesn't work with, the
> driver should be fixed to detect the running firmware version and not
> do things that the firmware doesn't support.  AND the firmware writer
> should also make it so the firmware doesn't barf on bad input and
> instead rejects it politely.

Agreed. The main issue here seems to be that the current patch
assumes that this feature is available. A proper approach would 
be to check if this feature is available before trying to use it.

Now, I dunno if version 8.9.0.0.81 has what's required for it to
work - or if KEY_IGTK require some custom firmware version.

If it works with such version, one way would be to add a check
for this specific version, disabling KEY_IGTK otherwise.

Also, someone from TI should be sending the newer version to
be added at linux-firmware.

I'll try to do a test maybe tomorrow.

> But I will say I'm making an educated guess; while I have played with
> the TI devices in the past, it was years ago and I won't claim to be
> an expert. I also am unable to fix it myself at this time.
> 
> I'd just rather see it fixed properly instead of a knee-jerk reaction
> of reverting it simply because the OP doesn't have current firmware.

> And let's revisit the discussion of having a kernel splat because an
> unrelated piece of code fails yet the driver does exactly what it is
> supposed to do. We shouldn't be dumping registers and stack-trace when
> the code that crashed has nothing to do with the registers and
> stack-trace outputted. It is a false positive.  A simple printk WARN
> or ERROR should output notifying us that the chip firmware has crashed
> and why.  IMHO.

Thanks,
Mauro