Does the reg_addr/reg_value reading work?

Ben Greear greearb at
Mon Jun 8 14:28:13 PDT 2015

On 06/08/2015 02:23 PM, Sebastian Gottschall wrote:
> Am 08.06.2015 um 22:02 schrieb Ben Greear:
>> On 06/08/2015 12:45 PM, Ben Greear wrote:
>>> On 06/08/2015 09:46 AM, Sebastian Gottschall wrote:
>>>> Am 08.06.2015 um 18:11 schrieb Ben Greear:
>>>>> I am not getting expected values when I try to read registers
>>>>> through the ath10k reg_addr/reg_value API.
>>>>> For instance, I tried reading a particular register 0x80e0
>>>>> (as defined in the firmware), and I get a zero value.  With a different
>>>>> API that I wrote to dump some specific registers over the WMI API,
>>>>> I get the expected value.
>>>>> # echo 0x80e0 > /debug/ieee80211/wiphy0/ath10k/reg_addr
>>>>> # cat /debug/ieee80211/wiphy0/ath10k/reg_value
>>>>> 0x000080e0:0x00000000
>>>>> # cat /debug/ieee80211/wiphy0/ath10k/fw_regs
>>>>>      ath10k Target Register Dump
>>>>>                =================
>>>>>              MAC-FILTER-ADDR-L32 0xd7ffffff
>>>>> ...
>>>>> Is there some trick I am missing?
>>>> 0x20000 offset makes the voodoo. you will find this offset within your firmware source too. take a look at the preconfigured register tables. these contain
>>>> already the ack,slot etc. settings.
>>>> but with a special macro surrounding it which defines that offset
>>>> echo 0x2080e0 > /debug/ieee80211/wiphy0/ath10k/reg_addr
>>> This crashes my kernel....I instrumented the place that crashed in ath10k/pci.h:
>>> [  100.676013] ath10k-pci-read32: ar ffff88020279ae20  ar_pci ffff88020279df08  offset: 0x2080e0
>>> [  100.676016]   ar_pci->mem: 0xffffc90019c80000
>>> [  100.676031] BUG: unable to handle kernel paging request at ffffc90019e880e0
>>> [  100.681752] IP: [<ffffffff81364ad4>] ioread32+0x9/0x2f
>>> Have you tried this on a 10.1.467 firmware?
>>> And, what kernel?  I'm trying 4.0.4+
>> I was using the wrong address should be 0x280e0.  Maybe the driver should still keep us from
>> crashing the whole kernel (while holding locks!), but at least it works when I put in
>> the right value.
> now that you say it. i see it too. but playing direct register writes can always lead to problematic scenarios. its a debug register. from my oppinion, a debug
> register should allow
> whatever is possible. even crashing something. its like using /dev/kmem

I am guessing the driver knows the pci address space that is could probably
just limit any access outside those bounds since they can never work anyway.

Anyway, I'll let someone else deal with it if they want.


Ben Greear <greearb at>
Candela Technologies Inc

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