From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2CCAE4CB58; Mon, 6 May 2024 22:31:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715034713; cv=none; b=WFSkhBgJlBnrIC5j2pPs9PQfQh13yB49NQVZQYq1AS587J/n5PnBGg4cOuPsIVR7CWQgq/RQJzoGi8he2Pj2xuT23qptaXwGriRNcvz/SQlUqPTTs7L/clEUN05oYjMGeLwDVd63DgVq9tLMGgtOFjeyN0KAQcBJQqmctk9X3ZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715034713; c=relaxed/simple; bh=MxL9KyUQPXgpKCWFrnBl9eSSaERBnN6J7itAyM6eMes=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=JTKmu0TRNS8CVj0UcPhYBrpPTMGRM7GYDtc3GIzoqhN9dqu+ldTfOc2XsLD69f9ieRxp1Wmx8vmL9yuI4jJAmwZ8UGzCf6BcYaCPyTrPwLPDEnj2dxdhGIi7YlFxsmV7Wf5u8+acux0fNcMejGeZ6AMTTJzEJK6pqpSCwD9EOY4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eIRSi6hs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eIRSi6hs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3494BC116B1; Mon, 6 May 2024 22:31:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715034711; bh=MxL9KyUQPXgpKCWFrnBl9eSSaERBnN6J7itAyM6eMes=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=eIRSi6hscHmlNqhd4Pn3Wy3brRAg9/VVqWitd16gHerwBPJKjkCOXqeYEKi5pxrMC rQPjLX22AHmvR9Qah7bPH9D/twK37kpQdEn71ksHdBo6DmBOlfhoyHmeF+rZm4Icje 1lfwURYuPQDBcwP7UO5mhGof+rXQAGHPHZwSdEmU2PctUfIc1WWaxa6XGSsRmI1mx2 EL0GVFkWi5lFuRPvtwUx8IbXKRVMrRn+yS6IJCMyzXQJiZpYIo+J2cowpMyJkk5Jmn buU6xGYoNyttwHUn4+8mda4H18FG3aWmAGk2mzpv/cGdTn4om8A2+zaqOPxGGwSl08 b3tKUTYcrFc9A== Date: Mon, 6 May 2024 17:31:49 -0500 From: Bjorn Helgaas To: Jim Quinlan Cc: linux-pci@vger.kernel.org, Nicolas Saenz Julienne , Bjorn Helgaas , Lorenzo Pieralisi , Cyril Brulebois , Phil Elwell , bcm-kernel-feedback-list@broadcom.com, Conor Dooley , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Florian Fainelli , Jim Quinlan , Krzysztof Kozlowski , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , open list , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , Lorenzo Pieralisi , Rob Herring Subject: Re: [PATCH v9 0/4] PCI: brcmstb: Configure appropriate HW CLKREQ# mode Message-ID: <20240506223149.GA1708699@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Apr 30, 2024 at 05:02:45PM -0400, Jim Quinlan wrote: > On Wed, Apr 3, 2024 at 5:39 PM Jim Quinlan wrote: > > > > v9 -- v8 was setting an internal bus timeout to accomodate large L1 exit > > latencies. After meeting the PCIe HW team it was revealed that the > > HW default timeout value was set low for the purposes of HW debugging > > convenience; for nominal operation it needs to be set to a higher > > value independent of this submission's purpose. This is now a > > separate commit. > > Bjorn, > > Did you have some time to look at this? Do you have any comments or questions? Sorry, I didn't realize you were waiting on me. I think Krzysztof W. will ultimately take care of these. I have some minor comments but overall I'm fine with this. > > -- With v8, Bjorne asked what was preventing a device from exceeding the > > time required for the above internal bus timeout. The answer to this > > is for us to set the endpoints' max latency {no-,}snoop value to > > something below this internal timeout value. If the endpoint > > respects this value as it should, it will not send an LTR request > > with a larger latency value and not put itself in a situation > > that requires more latency than is possible for the platform. > > > > Typically, ACPI or FW sets these max latency values. In most of our > > systems we do not have this happening so it is up to the RC driver to > > set these values in the endpoint devices. If the endpoints already > > have non-zero values that are lower than what we are setting, we let > > them be, as it is possible ACPI or FW set them and knows something > > that we do not. > > > > -- The "clkreq" commit has only been changed to remove the code that was > > setting the timeout value, as this code is now its own commit. > > > > v8 -- Un-advertise L1SS capability when in "no-l1ss" mode (Bjorn) > > -- Squashed last two commits of v7 (Bjorn) > > -- Fix DT binding description text wrapping (Bjorn) > > -- Fix incorrect Spec reference (Bjorn) > > s/PCIe Spec/PCIe Express Mini CEM 2.1 specification/ > > -- Text substitutions (Bjorn) > > s/WRT/With respect to/ > > s/Tclron/T_CLRon/ > > > > v7 -- Manivannan Sadhasivam suggested (a) making the property look like a > > network phy-mode and (b) keeping the code simple (not counting clkreq > > signal appearances, un-advertising capabilites, etc). This is > > what I have done. The property is now "brcm,clkreq-mode" and > > the values may be one of "safe", "default", and "no-l1ss". The > > default setting is to employ the most capable power savings mode. > > > > v6 -- No code has been changed. > > -- Changed commit subject and comment in "#PERST" commit (Bjorn, Cyril) > > -- Changed sign-off and author email address for all commits. > > This was due to a change in Broadcom's upstreaming policy. > > > > v5 -- Remove DT property "brcm,completion-timeout-us" from > > "DT bindings" commit. Although this error may be reported > > as a completion timeout, its cause was traced to an > > internal bus timeout which may occur even when there is > > no PCIe access being processed. We set a timeout of four > > seconds only if we are operating in "L1SS CLKREQ#" mode. > > -- Correct CEM 2.0 reference provided by HW engineer, > > s/3.2.5.2.5/3.2.5.2.2/ (Bjorn) > > -- Add newline to dev_info() string (Stefan) > > -- Change variable rval to unsigned (Stefan) > > -- s/implementaion/implementation/ (Bjorn) > > -- s/superpowersave/powersupersave/ (Bjorn) > > -- Slightly modify message on "PERST#" commit. > > -- Rebase to torvalds master > > > > v4 -- New commit that asserts PERST# for 2711/RPi SOCs at PCIe RC > > driver probe() time. This is done in Raspian Linux and its > > absence may be the cause of a failing test case. > > -- New commit that removes stale comment. > > > > v3 -- Rewrote commit msgs and comments refering panics if L1SS > > is enabled/disabled; the code snippet that unadvertises L1SS > > eliminates the panic scenario. (Bjorn) > > -- Add reference for "400ns of CLKREQ# assertion" blurb (Bjorn) > > -- Put binding names in DT commit Subject (Bjorn) > > -- Add a verb to a commit's subject line (Bjorn) > > -- s/accomodat(\w+)/accommodat$1/g (Bjorn) > > -- Rewrote commit msgs and comments refering panics if L1SS > > is enabled/disabled; the code snippet that unadvertises L1SS > > eliminates the panic scenario. (Bjorn) > > > > v2 -- Changed binding property 'brcm,completion-timeout-msec' to > > 'brcm,completion-timeout-us'. (StefanW for standard suffix). > > -- Warn when clamping timeout value, and include clamped > > region in message. Also add min and max in YAML. (StefanW) > > -- Qualify description of "brcm,completion-timeout-us" so that > > it refers to PCIe transactions. (StefanW) > > -- Remvove mention of Linux specifics in binding description. (StefanW) > > -- s/clkreq#/CLKREQ#/g (Bjorn) > > -- Refactor completion-timeout-us code to compare max and min to > > value given by the property (as opposed to the computed value). > > > > v1 -- The current driver assumes the downstream devices can > > provide CLKREQ# for ASPM. These commits accomodate devices > > w/ or w/o clkreq# and also handle L1SS-capable devices. > > > > -- The Raspian Linux folks have already been using a PCIe RC > > property "brcm,enable-l1ss". These commits use the same > > property, in a backward-compatible manner, and the implementaion > > adds more detail and also automatically identifies devices w/o > > a clkreq# signal, i.e. most devices plugged into an RPi CM4 > > IO board. > > > > Jim Quinlan (4): > > dt-bindings: PCI: brcmstb: Add property "brcm,clkreq-mode" > > PCI: brcmstb: Set reasonable value for internal bus timeout > > PCI: brcmstb: Set downstream maximum {no-}snoop LTR values > > PCI: brcmstb: Configure HW CLKREQ# mode appropriate for downstream > > device > > > > .../bindings/pci/brcm,stb-pcie.yaml | 18 ++ > > drivers/pci/controller/pcie-brcmstb.c | 161 +++++++++++++++++- > > 2 files changed, 170 insertions(+), 9 deletions(-) > > > > > > base-commit: 9f8413c4a66f2fb776d3dc3c9ed20bf435eb305e > > -- > > 2.17.1 > >