Re: [PATCH 3.6 4/4] ath9k_hw: enable PA linearization

["John W. Linville" <linville@tuxdriver.com>]

On Wed, Aug 08, 2012 at 08:59:15PM +0530, Rajkumar Manoharan wrote:
> On Wed, Aug 08, 2012 at 05:12:25PM +0200, Felix Fietkau wrote:
> > On 2012-08-08 4:55 PM, Rajkumar Manoharan wrote:
> > > On Tue, Aug 07, 2012 at 03:06:12PM +0200, Felix Fietkau wrote:
> > >> This feature had been disabled in ath9k because the code to support
> > >> it was incomplete, but now the code is in sync with the internal QCA
> > >> codebase, so it's time to enable it.
> > >> 
> > >> On many newer devices, the calibration is assumed to be done with PA
> > >> linearization enabled.
> > >> 
> > >> Tests with a particular AR933x device showed that the signal emitted
> > >> at full power was highly distorted and unreliable with PA linearization
> > >> disabled. With this patch, the signal becomes clear and stability
> > >> is improved.
> > >> 
> > > We faced stability issues with 938x chipsets when paprd is enabled. The commit
> > > 6f4810101a629b31b5427872a09ea092cfc5c4bd states one of the issue. Even if it
> > > helps for AR933x, let us enable it only for that chip alone.
> > That was in January 2011, lots of bugs have been fixed since then,
> > initvals have been updated, EEPROM code has changed, ...
> > 
> > The internal QCA codebase enables PAPRD for all AR93xx devices that
> > support it, meaning non-PAPRD tx receives much less test coverage there.
> > 
> > While this issue has only been visible on a particular AR933x device, I
> > believe this is not the only one that's going to be affected, as the
> > EEPROM of any new device is calibrated for PAPRD-enabled operation.
> > 
> > If you don't want to enable it now, when do you think would be the right
> > time to enable it? Before I sent this patch, I did a detailed code
> > review to make sure that any obvious code discrepancies in PAPRD between
> > the internal codebase and ath9k are dealt with.
> > 
> > What else is needed to get this issue sorted out?
> >
> Yes. it was disabled a long time back. Im completely fine with enabling the
> feature. I want to make sure that we should not endup again with the same issues.
> Atleast we should validite the one mentioned in the commit
> 6f4810101a629b31b5427872a09ea092cfc5c4bd

Any word on this validation?

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.