From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (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 9DBC41FECA1 for ; Wed, 20 Aug 2025 08:51:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755679892; cv=none; b=Ug2NhxDD/Br6srTNWFNcyswjZc+ENbGpcPHyYOtaCrSWR07+Prp4mL/ZgcJpS46waWlL7zvoRJhCVwF9pGDrpY4y91PKoRRzjH0mI8/wFV9RbTXvXmgeKRUOZUoc1HAxlWhtsatGWnmy2uydSvMo6YRJB8au9lnD8hqO6kzC9Qc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755679892; c=relaxed/simple; bh=/ds2ps/9fiQfLgnyFNZdjYCVb+MpjXSLLk6Lrhal8gY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Lel3ZkdxK7VktPjcWVF5nnbjsZer8lBMrjrAhDHP/GApHB49cfITaXk28ThO+kt4xNf06/vXcOP+d+cTKri16OmQwajxpdYhObk1uBd6rTrD6K9LwTKJ6mLqmoDA0biu53MHU8a1UvEZrqKCN+aFElVZFuJTNudMhRWXRxOvULQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=GhKKNkil; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="GhKKNkil" Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 57K1oa63025126 for ; Wed, 20 Aug 2025 08:51:30 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= Y4OMPtXQhdfS1IUPfrekUduc3f8tO3YSwKKo5NLCOZQ=; b=GhKKNkilIu9G/9Ca eNi6oFbDH8z4Sd+aRC/mlkWsbAJFSgM2bzmI3ygq7x0rs4sw2R36/Bt6ST42zrQ1 U7MNMRdCd6uN0zoNCbWXHRxOyYXulay+DxAQZzvAdkQSQFEKOv0mRsYwTbXW3TM6 VzWSlcihfaXgMF3Kovl7GWHRcuqHzI05IAGzV2CQZ4Aj/h26L32aomHpoFQtcvbh 5rxbTiIXKS3LCbTiGvidjupSmFwh/YdJWa/MH4FFu5hkd1/iMqHYRHPRSoRZaPB/ 8q0DwSLI+26DrZvp+7uJemkGCtMTYPsKupz1CmcGPEOLslBdDroAsb2zHr48j1KT 24cXUg== Received: from mail-pj1-f69.google.com (mail-pj1-f69.google.com [209.85.216.69]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 48n52a92tq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 20 Aug 2025 08:51:29 +0000 (GMT) Received: by mail-pj1-f69.google.com with SMTP id 98e67ed59e1d1-32326e21dd6so11901536a91.2 for ; Wed, 20 Aug 2025 01:51:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755679889; x=1756284689; 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=Y4OMPtXQhdfS1IUPfrekUduc3f8tO3YSwKKo5NLCOZQ=; b=FARtUUSkUpERBwf9uEMCM/F1mebK/GKc9qahmy3vU+3Fz2pNuPDoDkgYXtaFUDWrt8 LRNQWJzucIZ5x3pcMuBVW+wrpNKYltVVgA3g0LLNT5StDEV97nF7DK8lNSbDyBM4NAaF /f/XSvrlNT6tKBPfcBTvB2o1NLvUbVw1ESRCGOvaAjUSGfmJzqMzctaQO2NGRJekD642 J/r2qmaWkwNoJ++/4nXlYdnpBh7VSo7BMTztJrsxGgh2ToGossFQ3UWICkVOG+SjMcRn dUJbBmEWkWucwJT9C7y0OnfKRUvf+IxRpL9So7e717YGUBFUwuKLvi+SMnPbpkcf14cy kzSQ== X-Forwarded-Encrypted: i=1; AJvYcCX2dHWMq/144a5rvqEPM2N/nCDXrdcCdU+irex1xaKmGRY3SUDP/Wa2Hf8P9mfPMDjmIcRW8Oqy38/0nIo=@vger.kernel.org X-Gm-Message-State: AOJu0YxGEK1owrZvdgEUr/WdVCzE9yQQXQ9TaBB6ne8kT9XA8zbBgRZQ OFh9pXozhaUunwRpM7rNIuBuNuHBgRTjLosPUBdY5w2Cs/eXtmOLUl1x7lxvJWuCV2pfRhN+9+C OlXJUaGG5eq+N1jpeI49PB/IoZDEwfcSPVHKMuWfu7uHGC6VFBYWoV/2ceUEf1l6KCQI= X-Gm-Gg: ASbGncvFNkqLHmo0c+79L/xE2iPlMoiysoS6QHrBAm9yAc1DCzicipmXIBGxdnfXSPf 14xzoCG810/czSDiviO7ngCbOOHI/nlX9g/pc1x1DTSYB1fOJb8TydFl+XyxvvdU4RFfFZYgGmr aHwUkU0Zx1qowKNZTlOwQoo8DEdV3UHXgNJm89Dij182ACzQSyXnhwp7jQYQe7yf+dHgpBnfDqe bREsguNiuwgBeiJVclEKztmYG/7lB3MsCvtDvxdohDLBe3ri7oC8Yulh3h72yCcbgsnVMSY8ffg zdEK8PoNnddsSixmKz3DFy1gBZu6cMJ0t2JrQashKsr8Nyw2WCP+qiVNfzGzPZ/8fIoBr5+P X-Received: by 2002:a17:90b:48c6:b0:321:c0e3:a8ce with SMTP id 98e67ed59e1d1-324e140d2b1mr2658894a91.22.1755679888781; Wed, 20 Aug 2025 01:51:28 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGT7ZIz0JNmDoMWE9x4Ai5P9gO4JkYSgLlzLle23lvK2iLaSkN70tzxtR9pL+Q06Be6RHXqWw== X-Received: by 2002:a17:90b:48c6:b0:321:c0e3:a8ce with SMTP id 98e67ed59e1d1-324e140d2b1mr2658869a91.22.1755679888241; Wed, 20 Aug 2025 01:51:28 -0700 (PDT) Received: from [10.217.216.215] ([202.46.22.19]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-76e7d0d1a44sm4787237b3a.1.2025.08.20.01.51.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Aug 2025 01:51:27 -0700 (PDT) Message-ID: <7d3e5cf7-4167-4005-ba4b-c1915c254705@oss.qualcomm.com> Date: Wed, 20 Aug 2025 14:21:21 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] dt-bindings: interconnect: add clocks property to enable QoS on sa8775p To: Krzysztof Kozlowski , Georgi Djakov , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio Cc: Raviteja Laggyshetty , Dmitry Baryshkov , Bartosz Golaszewski , linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Tipton References: <20250808140300.14784-1-odelu.kukatla@oss.qualcomm.com> <20250808140300.14784-2-odelu.kukatla@oss.qualcomm.com> <90b51e31-3217-4483-bb5b-ec328665a723@kernel.org> <28b97952-1b67-411f-a7fb-ddd558739839@oss.qualcomm.com> Content-Language: en-US From: Odelu Kukatla In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: 4DKo4atpyZaFQspzeS-1BeVF_Uwk_Eq- X-Authority-Analysis: v=2.4 cv=B83gEOtM c=1 sm=1 tr=0 ts=68a58c91 cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=fChuTYTh2wq5r3m49p7fHw==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=VwQbUJbxAAAA:8 a=COk6AnOGAAAA:8 a=tJ9fhpcgm4yphQaQ0K8A:9 a=QEXdDO2ut3YA:10 a=rl5im9kqc5Lf4LNbBjHf:22 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-GUID: 4DKo4atpyZaFQspzeS-1BeVF_Uwk_Eq- X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIwMDAxMyBTYWx0ZWRfX6sU1WZbiZL0y DrwhYZ6bBpz8FNcCBzNfw/SKx69ki6itgclyYF8dKJGe0ZtO5kXofpjLAWFWaEup2iZgAZl3JSh b0K0PCVVeMGo1mhSqJzhCM3APGZEVmhJPA7gI+V/LpIZKeUT+KRIZ2UvOqa3kO7icq53r2HbpZJ +udK2zP50/jGg9xCy5EDajhJ6N5Lthgap3VmbE+tpAkV6lnT9+tHgwLtVMzF7BJ8mLB1JONEhlV gq9XHpu+FYh6GFfn+xufI7Ixq5Wt7boiJqaI0ymOb/PuZZN2u5O9pcKyQKrhqk8N1rXJjcXGWOD wF3GUZ+L3OyE1J/PK8ztYsqn8yuxEJTpqXeCdmBITd9kAxekLHWGyPNWOyqAVhQiRSc1nnSIEZI czB4x94CwRCFhBmzaF1ayobZR4x8sA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-20_03,2025-08-20_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 bulkscore=0 priorityscore=1501 suspectscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 clxscore=1015 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2508110000 definitions=main-2508200013 On 8/13/2025 11:32 AM, Krzysztof Kozlowski wrote: > On 13/08/2025 07:55, Odelu Kukatla wrote: >> >> >> On 8/12/2025 3:47 PM, Krzysztof Kozlowski wrote: >>> On 08/08/2025 16:02, Odelu Kukatla wrote: >>>> Add reg and clocks properties to enable the clocks required >>>> for accessing QoS configuration. >>> >>> >>> Nothing here explains why EXISTING hardware is being changed. I also >>> remember big discussions and big confusing patches regarding sa8775p >>> (its rename, dropping/changing all providers), and this patch feels like >>> pieces of it without proper justification. >>> >> Thanks for the review. >> I have added description in cover letter, i will add here as well in next revision.> And this is hidden ABI break, no justification, no mentioning either. >>> Again we are discussing basics of ABI breaking patches? >>> >> If you are talking ABI break if we load old DT which may lead to crash, we have .qos_requires_clocks flag which takes care of skipping QoS if required clocks are not enabled.we have addressed this issue through https://lore.kernel.org/all/20240704125515.22194-1-quic_okukatla@quicinc.com/ > > Format your emails correctly, it's difficult to read. > > Your binding did not require reg and clocks. Now it requires reg and > clocks. This is called ABI break. > > Please follow Qualcomm extensive upstreaming guide, it explains this, > doesn't it? Or follow writing bindings... > Thanks for your review and guidance. I agree that adding reg and clocks properties to existing bindings is an ABI break. The sa8775p is a relatively older platform, and when the interconnect provider driver was initially upstreamed, QoS configuration support was not available in the framework. As a result, QoS was not enabled at that time. The motivation for this change is that certain interconnect paths on sa8775p require specific clocks to be enabled to access QoS registers. QoS configuration is essential for managing latency and bandwidth across subsystems such as CPU, GPU, and multimedia engines. Without it, the system may experience performance degradation, especially under concurrent workloads. Enabling QoS improves system responsiveness and ensures more predictable behavior in high-throughput scenarios. We previously discussed ABI concerns when introducing QoS support on the SC7280 platform. To address this, we added a .qos_requires_clocks flag in the driver, which ensures that QoS configuration is skipped if the required clocks are not defined. This mechanism prevents crashes when older DTs are used, thereby preserving compatibility. I will update the commit message to include this justification. We also plan to follow a similar approach for other platforms like SA8775P, where the provider driver is already upstreamed and QoS enablement will be submitted as a separate patch series. Thanks again for your feedback. Best regards, Odelu > Best regards, > Krzysztof