[PATCH] ath10k: Allow setting coverage class

[Benjamin Berg]

On Mi, 2016-07-27 at 10:26 -0700, Ben Greear wrote:
> On 07/27/2016 01:33 AM, Benjamin Berg wrote:
> > 
> > Unfortunately ath10k does not generally allow modifying the coverage class
> > with the stock firmware and Qualcomm has so far refused to implement this
> > feature so that it can be properly supported in ath10k. If we however know
> > the registers that need to be modified for proper operation with a higher
> > coverage class, then we can do these modifications from the driver.
> > 
> > This patch implements this hack for first generation cards which are based
> > on a core that is similar to ath9k. The registers are modified in place and
> > need to be re-written every time the firmware sets them. To achieve this
> > the register status is verified after any event from the firmware.
> > 
> > The coverage class may not be modified temporarily right after the card
> > re-initializes the registers. This is for example the case during scanning.
> > 
> > A warning will be generated if the hack is not supported on the card or
> > unexpected values are hit. There is no error reporting for userspace
> > applications though (this is a limitation in the mac80211 driver
> > interface).
> > 
> > > > Thanks to Sebastian Gottschall <s.gottschall at dd-wrt.com> for initially
> > working on a userspace support for this. This patch wouldn't have been
> > possible without this documentation.
> 
> I would be concerned about the various resets firmware does to work around
> hardware hangs as well.  I don't think any events are generated for these, unless
> you count the dbglog messages?

Yeah, I am aware of the fact that the firmware may do internal resets
from time to time. The interesting question (and one for which I do not
know the answer) is whether we get a wmi or other event under all
conditions where the register may be rewritten due to a reset.

The current code will re-set the register value after any wmi event
including debug messages. If this is not enough, then the only solution
might be to periodically poll the register values instead of relying on
a received event.

Benjamin
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