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Subject: Re: WARNING: CPU: 1 PID: 2485 at
 drivers/net/wireless/intel/iwlwifi/pcie/trans.c:1752
 iwl_trans_pcie_grab_nic_access+0x110/0x120 [iwlwifi]
Thread-Topic: WARNING: CPU: 1 PID: 2485 at
 drivers/net/wireless/intel/iwlwifi/pcie/trans.c:1752
 iwl_trans_pcie_grab_nic_access+0x110/0x120 [iwlwifi]
Thread-Index: AQHRlqrAhqNxKohaXkWOO61GIGrhqp+KO2oA
Date: Fri, 15 Apr 2016 04:16:02 +0000
Message-ID: <1460693762.2648.5.camel@intel.com>
References: <20160415020710.GA2700@cz.tnic>
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On Fri, 2016-04-15 at 02:07 +0000, Borislav Petkov wrote:
> Hi,
> 
> so I'm seeing this when wlan0 tries to associate. On 4.6-rc2 + tip.
> After that, wifi is dead in the water. Anyone have a clue?
> 
> And 4.5 seems fine, I'm typing from it as we speak.
> ...

<snip>


> [  661.142657] ------------[ cut here ]------------
> [  661.142816] WARNING: CPU: 1 PID: 2485 at
> drivers/net/wireless/intel/iwlwifi/pcie/trans.c:1752
> iwl_trans_pcie_grab_nic_access+0x110/0x120 [iwlwifi]
> [  661.143231] Timeout waiting for hardware access (CSR_GP_CNTRL
> 0xffffffff)
> 

This means that we have an electrical issue that prevents us from
accessing the device over the PCI bus. BAR has been garbaged or alike.
Every time I tried to debug that from the driver side it has ...
failed. Because the "good" in the end did exhibit the problem. So,
unless you are ready to embark for a bisection journey (and hope that
this time when you type 'git bisect good' it is really 'good'), I can't
do much.
What I can suggest is to install our latest backport based tree on 4.5.
This will allow you to have an easily bisectable tree. But it might
very well be that 4.5 + latest driver (equivalent to 4.6 as far as
iwlwifi is concerned) will be fine.
The backport tree is here [1]. Unfortunately, that's the only thing I
can suggest for now.

[1] https://git.kernel.org/cgit/linux/kernel/git/iwlwifi/backport-iwlwi
fi.git/
> -- 
> Regards/Gruss,
>     Boris.
> 
> ECO tip #101: Trim your mails when you reply. Srsly.