Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:44708 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932210Ab2HJStW (ORCPT ); Fri, 10 Aug 2012 14:49:22 -0400 Date: Fri, 10 Aug 2012 14:44:45 -0400 From: "John W. Linville" To: Rajkumar Manoharan Cc: Felix Fietkau , linux-wireless@vger.kernel.org, rodrigue@qca.qualcomm.com Subject: Re: [PATCH 3.6 4/4] ath9k_hw: enable PA linearization Message-ID: <20120810184444.GE1950@tuxdriver.com> (sfid-20120810_205005_616441_F382B61D) References: <1344344772-49459-1-git-send-email-nbd@openwrt.org> <1344344772-49459-2-git-send-email-nbd@openwrt.org> <1344344772-49459-3-git-send-email-nbd@openwrt.org> <1344344772-49459-4-git-send-email-nbd@openwrt.org> <20120808145531.GB2041@vmraj-lnx.qualcomm.com> <502281D9.4030109@openwrt.org> <20120808152911.GD2041@vmraj-lnx.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20120808152911.GD2041@vmraj-lnx.qualcomm.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: 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.