From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF428C77B7C for ; Thu, 4 May 2023 15:41:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230459AbjEDPl2 (ORCPT ); Thu, 4 May 2023 11:41:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229768AbjEDPl1 (ORCPT ); Thu, 4 May 2023 11:41:27 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79C42E40; Thu, 4 May 2023 08:41:26 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 12CC963532; Thu, 4 May 2023 15:41:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53847C433D2; Thu, 4 May 2023 15:41:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683214885; bh=6eAF+PDzJKSUispa3X1kRM2MZ4pCLVUtY5fjeRCGXiA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=W8Oo7i3roM/RRef6hNcEKwGGoFpbQR86l34KO/NKH1a0qCn5JBSz0FWfUB3+HaeNE aLhSa1x2/xFf99elNs4U+71UWXgagW5a3BtU8JIDTjBUdq/gcJK5cSDbsTixoF4BIZ gF/XGhyxVJLgHJVSnF3g3OXIHy1vMYZtgS+vGW9VXw4uLmRBvZVOoCoT616t3oF82u cQXpUTlP+N9UFtEnRoiAKrEla/+JFYaWymO5VZtoeOkKZ38197H/zCECJ5d07sVRQF +zC8KfxBIYAzFgJ9c2JVcHBvvSCH9JLVCgdkw768ccchzjq4WmkCebAd2Og2dovStE vVIpopmID/A5w== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1pub5J-00014L-JQ; Thu, 04 May 2023 17:41:34 +0200 Date: Thu, 4 May 2023 17:41:33 +0200 From: Johan Hovold To: Bjorn Andersson Cc: Vinod Koul , Kishon Vijay Abraham I , Bjorn Andersson , Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/7] phy: qcom-qmp-combo: Introduce orientation variable Message-ID: References: <20230425034010.3789376-1-quic_bjorande@quicinc.com> <20230425034010.3789376-4-quic_bjorande@quicinc.com> <20230504032907.GF870858@hu-bjorande-lv.qualcomm.com> <20230504151633.GH870858@hu-bjorande-lv.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230504151633.GH870858@hu-bjorande-lv.qualcomm.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, May 04, 2023 at 08:16:33AM -0700, Bjorn Andersson wrote: > On Thu, May 04, 2023 at 03:44:53PM +0200, Johan Hovold wrote: > > On Wed, May 03, 2023 at 08:29:07PM -0700, Bjorn Andersson wrote: > > > On Tue, May 02, 2023 at 01:48:16PM +0200, Johan Hovold wrote: > > > > On Mon, Apr 24, 2023 at 08:40:06PM -0700, Bjorn Andersson wrote: > > > > > > > static void qmp_v3_dp_aux_init(struct qmp_combo *qmp); > > > > > @@ -1955,29 +1962,23 @@ static void qmp_v3_configure_dp_tx(struct qmp_combo *qmp) > > > > > static bool qmp_combo_configure_dp_mode(struct qmp_combo *qmp) > > > > > { > > > > > u32 val; > > > > > - bool reverse = false; > > > > > + bool reverse = qmp->orientation == TYPEC_ORIENTATION_REVERSE; > > > > > > It also looks like these callbacks end up being called without holding > > > > the qmp->phy_mutex via phy->power_on(). Perhaps there is no risk for a > > > > concurrent switch notification and dp phy power-on but it's not that > > > > obvious. > > > > > It seems we're arriving here from hpd_event_thread(), while > > > phy_power_on() and phy_power_off() will be called in some other context. > > > I've not been able to convince myself if DP driver ensures ordering, or > > > if we have an existing race here... > > > > > Unless you insist, I would prefer to follow up with an additional patch > > > once we've landed this series. The fix will depend on the phy_mutex > > > shuffling patch anyways... > > > > Sure. > > > > But perhaps you can just move the orientation == qmp->orientation check > > under the mutex in qmp_combo_typec_switch_set() for now (in case I > > forgot to point that out earlier). > > > > qmp_combo_probe() and qmp_combo_typec_switch_set() are the only writers > to qmp->orientation, so that check can't race with any updates and hence > doesn't need to be protected. Only if you happen to know that the callers of qmp_combo_typec_switch_set() are serialised, right? That happens to be the case for pmic_glink, but it may not be the case generally. > Reading the code again, qmp_combo_configure_dp_mode() is invoked from > phy_power_on(), not the hpd_event_thread(), as I claimed yesterday. Yeah, but phy_power_on() is typically called from that thread. But perhaps not only from there. > But we shouldn't do qmp_combo_dp_power_on() in parallel with the > reinitialization following a switch in orientation, qmp->orientation > might change, but we definitely would have two contexts reconfiguring > the hardware simultaneously - perhaps this was the cause for the 10% > crashes I hit when trying to extend this to handle typec_mux as well... > > I will grab the phy_mux in qmp_combo_configure_dp_mode() as well, thanks > for "insisting" :) :) Johan