On Wed, 2017-09-06 at 16:27 -0700, Linus Torvalds wrote:

This pull request completely breaks Intel wireless for me.

This is my trusty old XPS 13 (9350), using Intel Wireless 8260 (rev 3a).

That remains a very standard Intel machine with absolutely zero odd
things going on.

The firmware is iwlwifi-8000C-28.ucode from
iwl7260-firmware-25.30.13.0-75.fc26.noarch, and the kernel reports

  iwlwifi 0000:3a:00.0: loaded firmware version 27.455470.0 op_mode iwlmvm

the thing starts acting badly with this:

  iwlwifi 0000:3a:00.0: FW Error notification: type 0x00000000 cmd_id 0x04
  iwlwifi 0000:3a:00.0: FW Error notification: seq 0x0000 service 0x00000004
  iwlwifi 0000:3a:00.0: FW Error notification: timestamp 0x            5D84
  iwlwifi 0000:3a:00.0: Microcode SW error detected.  Restarting 0x2000000.
  iwlwifi 0000:3a:00.0: Start IWL Error Log Dump:
  iwlwifi 0000:3a:00.0: Status: 0x00000100, count: 6
  iwlwifi 0000:3a:00.0: Loaded firmware version: 27.455470.0
  iwlwifi 0000:3a:00.0: 0x00000038 | BAD_COMMAND
  iwlwifi 0000:3a:00.0: 0x00A002F0 | trm_hw_status0
  ...
  iwlwifi 0000:3a:00.0: 0x00000000 | isr status reg
  ieee80211 phy0: Hardware restart was requested
  iwlwifi 0000:3a:00.0: FW error in SYNC CMD MAC_CONTEXT_CMD

This seems to be a problem with backwards-compatibility with FW version
27.  We are now in version 31[1] and upgrading will probably fix that.

But obviously the driver should not fail miserably like this with
version 27, because it claims to support it still.

I'm looking into this now and will provide a fix asap.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/iwlwifi-8000C-31.ucode


--
Cheers,
Luca.