Return-path: Received: from sabertooth01.qualcomm.com ([65.197.215.72]:58650 "EHLO sabertooth01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752741Ab3HEQkh (ORCPT ); Mon, 5 Aug 2013 12:40:37 -0400 From: Kalle Valo To: Michal Kazior CC: Bartosz Markowski , , Subject: Re: [PATCH v2] ath10k: add SoC power save option to PCI features map References: <1375430329-23352-1-git-send-email-bartosz.markowski@tieto.com> Date: Mon, 5 Aug 2013 19:40:14 +0300 In-Reply-To: (Michal Kazior's message of "Mon, 5 Aug 2013 15:31:31 +0200") Message-ID: <87iozkf5w0.fsf@kamboji.qca.qualcomm.com> (sfid-20130805_184040_855366_49B7726C) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-wireless-owner@vger.kernel.org List-ID: Michal Kazior writes: > On 2 August 2013 09:58, Bartosz Markowski wrote: >> Unify the PCI options location. >> >> By default the SoC PS option is disabled to boost the >> performance and due to poor stability on early HW revisions. >> In future we can remove the module parameter and turn on/off >> the PS for given hardware. >> >> This change also makes the pci module parameter for SoC PS static. >> >> Signed-off-by: Bartosz Markowski > > Hmm.. I'm worried about pci wake/sleep locking: > > (a) pci_wake() (awake count =1) > (a) do something > Now, if pci_sleep() and pci_wake() happen simultaneously/are > preempted splitting primitive operations to: > (a) pci_sleep(): decrease awake count (=0) > (b) pci_wake(): increase awake count (=1), iowrite, wait for awake, return > (a) pci_sleep(): iowrite(). return > The flow in (b) now thinks the device is awake, but it's not > guaranteed to be anymore because it has been put to sleep by (a). Yeah, there's a race alright. I wonder if I have ever seen a proper use of a atomic variable in a wireless driver :) But this doesn't prevent taking this patch as the race has existed since the beginning, right? -- Kalle Valo