Unable to read firmware registers on crash?

Ben Greear greearb at candelatech.com
Tue Feb 3 20:28:29 PST 2015

Well, it seems to work at least when I crash it nicely with the
debugfs firmware-assert hooks.  Tested on x86...if I have endian
issues, things might go poorly on other platforms.

Here is patch I am using in ath10k...  I added similar logic to the
CT firmware.  Now, will have to see if we can reproduce the crash where
CE transport totally fails...


Comments welcome on the patch, though it has little to no chance of ever
making it upstream...


On 02/03/2015 07:45 PM, Ben Greear wrote:
> On 02/03/2015 06:26 AM, Michal Kazior wrote:
>> On 3 February 2015 at 14:57, Ben Greear <greearb at candelatech.com> wrote:
>>> That sounds reasonable.  Do you know of any example code that accesses
>>> a target register or two with the MMIO logic on the host?  I think firmware
>>> has some examples of how
>>> to fiddle with registers, so I think I can make a stab at that part....
>>  From what I understand the MMIO space is shared between host and
>> target program so there's no need for any special handling. You can
>> look for FW_IND_EVENT_PENDING and FW_INDICATOR_ADDRESS usage both in
>> firmware and ath10k - it's already used to notify host about a crash.
>> It should be pretty straightforward. The indicator address itself
>> seems to be a scratch register already and there are a few more so you
>> should be able to design a ping-pong protocol to pass data.
> While implementing this, I ran into a question:
>  From what I can tell, the ath10k_pci_read32 and ath10k_pci_write32
> are treated like they return and write data in host-byte-order.
> But, iowrite32 and ioread32 are defined to be pci-byte-order which
> is little-endian?
> http://comments.gmane.org/gmane.linux.kernel/1042371
> (or is that bad info?)
> Do we need to be converting values to little-endian before
> writing them?
> And upon, read, do we need to convert them to host order?
> I guess we must not since it seems things mostly work now, but I
> am not sure why that is...
> Thanks,
> Ben
>> Michał

Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

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