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 270ECC46CA1 for ; Mon, 16 Oct 2023 12:57:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231444AbjJPM5R (ORCPT ); Mon, 16 Oct 2023 08:57:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230017AbjJPM5Q (ORCPT ); Mon, 16 Oct 2023 08:57:16 -0400 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 674ABAD; Mon, 16 Oct 2023 05:57:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697461034; x=1728997034; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=33VN831uWAKG7f4eIn44PpDJgWUV0McuEtJM+oSWIh4=; b=Xf/12PbHv7oGM5zCun8OHZP2oOMZxmhEH6ZJ5/lUhqXfYAqUQEckGFxg uhBxh6kGxA949FC6FN2zZBWyvKJUifUexGABTLbcEAf1OWjx7mkTVa8Th xcjaHeb44AZsDmv4pcw7gCTgvOCLukytu2kdP8klIQpb52JMIVDCQIG4w L1wXdn9S2w13DghDuKXdK3k7ITNbCmmBqcE7MLPz8phNpEUDr+k3GznJW WWb2zBxOO8yfgVXUiNz7waOrIXsq+sVisX6XfG9x/jLpM0Arh3YOUHPEd Uq4Y8ewK7wuy0L394EulosARaZq0Chiyy9OV9IB39oKpZLPVvwycCESLJ g==; X-IronPort-AV: E=McAfee;i="6600,9927,10863"; a="4130579" X-IronPort-AV: E=Sophos;i="6.03,229,1694761200"; d="scan'208";a="4130579" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2023 05:57:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10863"; a="1087063948" X-IronPort-AV: E=Sophos;i="6.03,229,1694761200"; d="scan'208";a="1087063948" Received: from rhaeussl-mobl.ger.corp.intel.com (HELO bhoerz-mobl1.ger.corp.intel.com) ([10.252.59.103]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2023 05:57:07 -0700 Date: Mon, 16 Oct 2023 15:57:05 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Bjorn Helgaas cc: linux-pci@vger.kernel.org, Lorenzo Pieralisi , Rob Herring , =?ISO-8859-2?Q?Krzysztof_Wilczy=F1ski?= , Lukas Wunner , "Rafael J . Wysocki" , Heiner Kallweit , Emmanuel Grumbach , LKML , Bjorn Helgaas , ath10k@lists.infradead.org, ath11k@lists.infradead.org, ath12k@lists.infradead.org, intel-wired-lan@lists.osuosl.org, linux-arm-kernel@lists.infradead.org, linux-bluetooth@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-rdma@vger.kernel.org, linux-wireless@vger.kernel.org, Netdev Subject: Re: [PATCH v2 05/13] PCI/ASPM: Add pci_enable_link_state() In-Reply-To: <20231013164850.GA1118214@bhelgaas> Message-ID: <9da430a3-9336-8e75-7385-3d5ddcb6cb7@linux.intel.com> References: <20231013164850.GA1118214@bhelgaas> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-1750157713-1697461032=:1986" Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1750157713-1697461032=:1986 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT On Fri, 13 Oct 2023, Bjorn Helgaas wrote: > On Thu, Oct 12, 2023 at 03:53:39PM +0300, Ilpo Järvinen wrote: > > On Wed, 11 Oct 2023, Bjorn Helgaas wrote: > > > On Mon, Sep 18, 2023 at 04:10:55PM +0300, Ilpo Järvinen wrote: > > > > pci_disable_link_state() lacks a symmetric pair. Some drivers want to > > > > disable ASPM during certain phases of their operation but then > > > > re-enable it later on. If pci_disable_link_state() is made for the > > > > device, there is currently no way to re-enable the states that were > > > > disabled. > > > > > > pci_disable_link_state() gives drivers a way to disable specified ASPM > > > states using a bitmask (PCIE_LINK_STATE_L0S, PCIE_LINK_STATE_L1, > > > PCIE_LINK_STATE_L1_1, etc), but IIUC the driver can't tell exactly > > > what changed and can't directly restore the original state, e.g., > > > > > > - PCIE_LINK_STATE_L1 enabled initially > > > - driver calls pci_disable_link_state(PCIE_LINK_STATE_L0S) > > > - driver calls pci_enable_link_state(PCIE_LINK_STATE_L0S) > > > - PCIE_LINK_STATE_L0S and PCIE_LINK_STATE_L1 are enabled now > > > > > > Now PCIE_LINK_STATE_L0S is enabled even though it was not initially > > > enabled. Maybe that's what we want; I dunno. > > > > > > pci_disable_link_state() currently returns success/failure, but only > > > r8169 and mt76 even check, and only rtl_init_one() (r8169) has a > > > non-trivial reason, so it's conceivable that it could return a bitmask > > > instead. > > > > It's great that you suggested this since it's actually what also I've been > > started to think should be done instead of this straightforward approach > > I used in V2. > > > > That is, don't have the drivers to get anything directly from LNKCTL > > but they should get everything through the API provided by the > > disable/enable calls which makes it easy for the driver to pass the same > > value back into the enable call. > > > > > > Add pci_enable_link_state() to remove ASPM states from the state > > > > disable mask. > > > > > > > > Signed-off-by: Ilpo Järvinen > > > > --- > > > > drivers/pci/pcie/aspm.c | 42 +++++++++++++++++++++++++++++++++++++++++ > > > > include/linux/pci.h | 2 ++ > > > > 2 files changed, 44 insertions(+) > > > > > > > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > > > > index 91dc95aca90f..f45d18d47c20 100644 > > > > --- a/drivers/pci/pcie/aspm.c > > > > +++ b/drivers/pci/pcie/aspm.c > > > > @@ -1117,6 +1117,48 @@ int pci_disable_link_state(struct pci_dev *pdev, int state) > > > > } > > > > EXPORT_SYMBOL(pci_disable_link_state); > > > > > > > > +/** > > > > + * pci_enable_link_state - Re-enable device's link state > > > > + * @pdev: PCI device > > > > + * @state: ASPM link states to re-enable > > > > + * > > > > + * Enable device's link state that were previously disable so the link is > > > > > > "state[s] that were previously disable[d]" alludes to the use case you > > > have in mind, but I don't think it describes how this function > > > actually works. This function just makes it possible to enable the > > > specified states. The @state parameter may have nothing to do with > > > any previously disabled states. > > > > Yes, it's what I've been thinking between the lines. But I see your point > > that this API didn't make it easy/obvious as is. > > > > Would you want me to enforce it too besides altering the API such that the > > states are actually returned from disable call? (I don't personally find > > that necessary as long as the API pair itself makes it obvious what the > > driver is expect to pass there.) > > This was just a comment about the doc not matching the function > behavior. > > I think we have to support pci_enable_link_state() even if the driver > hasn't previously called pci_disable_link_state(), so drivers have to > be able to specify the pci_enable_link_state() @state from scratch. > > Does that answer the enforcement question? Yes. -- i. > I don't think we can > really enforce anything other than that @state specifies valid ASPM > states. > > Bjorn > --8323329-1750157713-1697461032=:1986--