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 5AA62C7EE2D for ; Sat, 25 Feb 2023 10:00:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229495AbjBYKAz (ORCPT ); Sat, 25 Feb 2023 05:00:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229458AbjBYKAy (ORCPT ); Sat, 25 Feb 2023 05:00:54 -0500 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55D531DB98 for ; Sat, 25 Feb 2023 02:00:52 -0800 (PST) Received: by mail-wm1-x335.google.com with SMTP id o11-20020a05600c4fcb00b003eb33ea29a8so493533wmq.1 for ; Sat, 25 Feb 2023 02:00:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=BOT0daIqYTUXHjO378HNb59W9he2Y4mmNd7ANSY/Y+o=; b=OKaiNDgjPSyLjeH5ZmcvHRIjucbaPGoZiUn22mN1HvjIEj/ahtqbj6yjWyOVWuhipY CKo8XEz/yxYWxB+zuYreM3zVwj43/T9e46w6UFoDp+d7TJzFX5X2J3mFQxOXXa3aL4ie WJLgW1mk1UjKEzteJYWaCLJLFSk1PJurAsagnLT0EmVzlznEv5qQiXpMtmizfpi/5G8Y bWngyqyMC9QO00LOZwrhrfbFnxKHGqEA0KVdtiZcDfsQtJAeRLDQGcJudj4drwwRNVnU bX0DqEHlbv2flhWHBGsO/cSwpuGsHkhP0KRXxKkAuioDV2kdIc0VsOtk2MaWCO7iAWjF BlAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=BOT0daIqYTUXHjO378HNb59W9he2Y4mmNd7ANSY/Y+o=; b=5Jh7j8Es/644usz/Jt/FMe9nzXaPtEZz9I3QQJ0/xKqKGCnvxoO7+8ONL7/AzzJRFQ x5ukmrCSMloaP2cTXcBbgOt5QsEz/+krWBEdV0klgfoc0VWQ8gPYT+SGmn4sNy0vM1pz nAoxMk+sUix7gdHfJnIptsL8SDC8WTsqjrrZDY+5Dn1+k9XExeeZ1tUg479OiTrEJfEP z08+o4AVtQa5YUnPKClM8OsK0gl8+d/3fup1RygOVoP0sJyZDhz8Uhxtk/KgafYe+6Un I2+y+3dXa5Qj6PQhwQ+I040JLTz988l4i3XzISh0YWHAGOOBVhM/hBFAu9CPRr/9CQm9 UWAw== X-Gm-Message-State: AO0yUKWR2p0STnlKZw2I8d1gkEvjsXPnsxApywxjsnZRNIrP1f5C8RTY WY8pUYKy1t7Lzi36Kqk+AnZpKw== X-Google-Smtp-Source: AK7set/lZdy5+f/JBn8126aa7oflTbLTWZlZXIwwPxt36QIs5XE+jeRYRpMGz9n3f4Az/NyHRN+jiw== X-Received: by 2002:a05:600c:ac8:b0:3e2:91c:7cb7 with SMTP id c8-20020a05600c0ac800b003e2091c7cb7mr13427963wmr.39.1677319250774; Sat, 25 Feb 2023 02:00:50 -0800 (PST) Received: from [192.168.1.20] ([178.197.216.144]) by smtp.gmail.com with ESMTPSA id f5-20020a1c6a05000000b003d9aa76dc6asm5623414wmc.0.2023.02.25.02.00.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 25 Feb 2023 02:00:50 -0800 (PST) Message-ID: <28c72c1a-df7d-db05-f32f-23b170b96db5@linaro.org> Date: Sat, 25 Feb 2023 11:00:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v1 1/2] dt-bindings: PCI: dwc: Add snps,skip-wait-link-up To: Sajid Dalvi , Jingoo Han , Gustavo Pimentel , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= , Rob Herring , Bjorn Helgaas , Krzysztof Kozlowski Cc: kernel-team@android.com, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230224195749.818282-1-sdalvi@google.com> <20230224195749.818282-2-sdalvi@google.com> <2e4964c1-0831-c156-3372-81a56f8d623e@linaro.org> Content-Language: en-US From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 24/02/2023 23:09, Sajid Dalvi wrote: > On Fri, Feb 24, 2023 at 3:29 PM Krzysztof Kozlowski > wrote: >> >> On 24/02/2023 22:27, Sajid Dalvi wrote: >>> On Fri, Feb 24, 2023 at 2:40 PM Krzysztof Kozlowski >>> wrote: >>>> >>>> On 24/02/2023 20:57, Sajid Dalvi wrote: >>>>> When the Root Complex is probed, the default behavior is to spin in a loop >>>>> waiting for the link to come up. In some systems the link is not brought up >>>>> during probe, but later in the context of an end-point turning on. >>>>> This property will allow the loop to be skipped. >>>>> >>>>> Signed-off-by: Sajid Dalvi >>>>> --- >>>> >>>> Thank you for your patch. There is something to discuss/improve. >>>> >>>>> Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml | 8 ++++++++ >>>>> 1 file changed, 8 insertions(+) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml >>>>> index 1a83f0f65f19..0b8950a73b7e 100644 >>>>> --- a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml >>>>> +++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml >>>>> @@ -197,6 +197,14 @@ properties: >>>>> - contains: >>>>> const: msi >>>>> >>>>> + snps,skip-wait-link-up: >>>>> + $ref: /schemas/types.yaml#/definitions/flag >>>>> + description: >>>>> + When the Root Complex is probed, the default behavior is to spin in a >>>>> + loop waiting for the link to come up. In some systems the link is not >>>>> + brought up during probe, but later in the context of an end-point turning >>>>> + on. This property will allow the loop to be skipped. >>>> >>>> I fail to see how probe behavior is related to properties of hardware. >>>> You describe OS behavior, not hardware. This does not look like >>>> belonging to DT. >>>> >>>> >>>> Best regards, >>>> Krzysztof >>> >>> Thanks for your response Krzysztof. >>> The hardware configuration of the system determines whether an >>> endpoint device is available during host init. If it isn't available >>> on a particular and dedicated pcie interface, we should skip waiting >>> for the link to be up. For other interfaces, possibly even on the same >>> system, where a device is present or maybe present we should wait for >>> the link to come up. >> >> Keep discussions public. >> >> Your commit and property description mentions probe, which is nothing >> related to hardware. Why the device would not be available during host >> init (I understand we do not talk about hotplug as it is already >> supported by Linux) in a way it is hardware property, not OS? >> >> Best regards, >> Krzysztof >> > > + everyone else I mistakenly didn't reply to earlier > > If I understand you correctly, the usage of probe is misleading > because it doesn't have anything to do with the hardware. > So your recommendation is to replace probe with device init, in the > description of the property and the commit message? No, I asked there a question for which we need answer. device init is also OS task... You need to explain why this is a property of hardware, not OS behavior. Best regards, Krzysztof