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Wed, 28 Feb 2024 06:48:18 +0000 (GMT) Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA05.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 41S6mH8x017390 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 28 Feb 2024 06:48:17 GMT Received: from [10.216.14.152] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Tue, 27 Feb 2024 22:48:09 -0800 Message-ID: Date: Wed, 28 Feb 2024 12:18:06 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH v7 7/7] PCI: qcom: Add OPP support to scale performance state of power domain Content-Language: en-US To: Bjorn Helgaas CC: Bjorn Andersson , Konrad Dybcio , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= , Rob Herring , Bjorn Helgaas , Krzysztof Kozlowski , Conor Dooley , Manivannan Sadhasivam , Rob Herring , Johan Hovold , Brian Masney , Georgi Djakov , , , , , , , , , References: <20240227234549.GA251722@bhelgaas> From: Krishna Chaitanya Chundru In-Reply-To: <20240227234549.GA251722@bhelgaas> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: XTAq6dwlcIf-let6VF0nOWobX5a97s3y X-Proofpoint-ORIG-GUID: XTAq6dwlcIf-let6VF0nOWobX5a97s3y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-28_04,2024-02-27_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 bulkscore=0 mlxlogscore=999 impostorscore=0 malwarescore=0 mlxscore=0 suspectscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 spamscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2402120000 definitions=main-2402280051 On 2/28/2024 5:15 AM, Bjorn Helgaas wrote: > On Tue, Feb 27, 2024 at 05:36:38PM -0600, Bjorn Helgaas wrote: >> On Fri, Feb 23, 2024 at 08:18:04PM +0530, Krishna chaitanya chundru wrote: >>> QCOM Resource Power Manager-hardened (RPMh) is a hardware block which >>> maintains hardware state of a regulator by performing max aggregation of >>> the requests made by all of the clients. > >>> It is manadate to scale the performance state based up on the PCIe speed >>> link operates so that SoC can run under optimum power conditions. >> >> It sounds like it's more power efficient, but not actually >> *mandatory*. Maybe something like this? >> >> The SoC can be more power efficient if we scale the performance >> state based on the aggregate PCIe link speed. > > Actually, maybe it would be better to say "aggregate PCIe link > bandwidth", because we use "speed" elsewhere (PCIE_SPEED2MBS_ENC(), > etc) to refer specifically to the data rate independent of the width. > >>> Add Operating Performance Points(OPP) support to vote for RPMh state based >>> upon the speed link is operating. >> >> "... based on the link speed." > > "... based on the aggregate link bandwidth." > >>> In PCIe certain speeds like GEN1x2 & GEN2x1 or GEN3x2 & GEN4x1 use >>> same bw and frequency and thus the OPP entry, so use frequency based >>> search to reduce number of entries in the OPP table. >> >> GEN1x2, GEN2x1, etc are not "speeds". I would say: >> >> Different link configurations may share the same aggregate speed, >> e.g., a 2.5 GT/s x2 link and a 5.0 GT/s x1 link have the same speed >> and share the same OPP entry. > > Different link configurations may share the same aggregate > bandwidth, e.g., a 2.5 GT/s x2 link and a 5.0 GT/s x1 link > have the same bandwidth and share the same OPP entry. - I will update the commit message as suggested in my next series. - Krishna Chaitanya.