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 50B21C6FD1F for ; Tue, 14 Mar 2023 17:16:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230201AbjCNRQL (ORCPT ); Tue, 14 Mar 2023 13:16:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229962AbjCNRQK (ORCPT ); Tue, 14 Mar 2023 13:16:10 -0400 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7D47637E6; Tue, 14 Mar 2023 10:16:07 -0700 (PDT) Received: from pps.filterd (m0279871.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 32EFrduA007258; Tue, 14 Mar 2023 17:16:03 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=qcppdkim1; bh=7iU9Fdci41agMBqqTqvb2fq8ed7Zx5c1MmivljDBFE8=; b=LLXnZuUJXNyqx5Hht9Q19VeTe+jSNkR+5RFChUrwq+ZkX0sDSHdVaU6o1UD6kU5mvvaA vQniDnVZ8QFiS3h9zhYgFLdBXtaXPJcxhhUguPbSSXcV5m5iIPFpavysBIIWBzO/h1yr iB4CLIbrJkEdKZnhfoR41ZOWi6ES/Aly0XOYkrQd/X8gTFTKiKkttcZdv5hOsBp79G87 FlVeLDse8/qd8tPaB8ceacfakdWNY0qd0h1gwAWypGKgJ0+ZEs7hlGWbuo0pmYJ46faD l5EE0XewbZOpZrbbMGfNlVakaKklkOumeGMIyw/es/fz3hJTDmKVugHYc2/jLADuq2fP Aw== Received: from nalasppmta05.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3pau4mgdht-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 14 Mar 2023 17:16:03 +0000 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 32EHG2ra008009 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 14 Mar 2023 17:16:02 GMT Received: from [10.216.8.135] (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 15.2.986.41; Tue, 14 Mar 2023 10:15:56 -0700 Message-ID: Date: Tue, 14 Mar 2023 22:45:47 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH V2 4/6] regulator: qcom_smd: Add support to define the bootup voltage To: Konrad Dybcio , Mark Brown CC: , , , , , , , , , , , , , , References: <20230217142030.16012-1-quic_devipriy@quicinc.com> <20230217142030.16012-5-quic_devipriy@quicinc.com> <907628d1-b88d-5ac6-ed9d-7f63e2875738@linaro.org> <39f73580-f263-de0e-6819-89c3f4c75c3a@quicinc.com> <8ce07abd-2d02-69d2-8dc6-fe11525aecda@linaro.org> <11b05b9f-b969-6648-2204-2da5f8465c96@quicinc.com> <751e5129-3c11-0156-719e-3fe996a149be@quicinc.com> <3f434777-c4b6-272f-1971-f9adf3faefe4@linaro.org> Content-Language: en-US From: Devi Priya In-Reply-To: <3f434777-c4b6-272f-1971-f9adf3faefe4@linaro.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] 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: iw_Xq2J42y_Tbd7EdR8LV69zPF0guG7h X-Proofpoint-ORIG-GUID: iw_Xq2J42y_Tbd7EdR8LV69zPF0guG7h X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-14_10,2023-03-14_02,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 phishscore=0 spamscore=0 clxscore=1015 priorityscore=1501 bulkscore=0 suspectscore=0 malwarescore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2303140140 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 3/8/2023 3:57 PM, Konrad Dybcio wrote: > > > On 7.03.2023 07:55, Devi Priya wrote: >> >> >> On 3/6/2023 6:39 PM, Devi Priya wrote: >>> >>> >>> On 3/3/2023 6:57 PM, Konrad Dybcio wrote: >>>> >>>> >>>> On 3.03.2023 14:21, Devi Priya wrote: >>>>> >>>>> >>>>> On 2/23/2023 4:31 AM, Mark Brown wrote: >>>>>> On Wed, Feb 22, 2023 at 11:11:42PM +0100, Konrad Dybcio wrote: >>>>>> >>>>>>> Thinking about it again, this seems like something that could be >>>>>>> generalized and introduced into regulator core.. Hardcoding this >>>>>>> will not end well.. Not to mention it'll affect all mp5496-using >>>>>>> boards that are already upstream. >>>>>> >>>>>>> WDYT about regulator-init-microvolts Mark? >>>>>> >>>>>> The overwhelming majority of devices that have variable voltages >>>>>> support readback, these Qualcomm firmware devices are pretty much >>>>>> unique in this regard.  We don't want a general property to set a >>>>>> specific voltage since normally we should be using the >>>>>> constraints and don't normally need to adjust things immediately >>>>>> since we can tell what the current voltage is. >>>>>> >>>>>> This is pretty much just going to be a device specific bodge, >>>>>> ideally something that does know what the voltage is would be >>>>>> able to tell us at runtime but if that's not possible then >>>>>> there's no good options.  If the initial voltage might vary based >>>>>> on board then a device specific DT property might be less >>>>>> terrible, if it's determined by the regulator the current code >>>>>> seems fine.  Or just leave the current behavour, if the >>>>>> constraints are accurate then hopefully a temporary dip in >>>>>> voltage is just inelegant rather than an issue.  Indeed the >>>>>> current behaviour might well save power if you've got a voltage >>>>>> range configured and nothing actually ever gets round to setting >>>>>> the voltage (which is depressingly common, people seem keen on >>>>>> setting voltage ranges even when the voltage is never varied in >>>>>> practice). >>>>> >>>>> Hi Mark, The initial bootup voltage is actually blown into the OTP register of the PMIC and it remains the same across boards for IPQ9574 SoC. >>>> But what about IPQ6018 which also uses MP5496? That's also gonna >>>> set the voltage on there, it may be too high/low.. >> For IPQ6018, the bootup voltage is the same as that of IPQ9574 which is >> 875mV > Okay, but what about any other design that employs or may employ > MP5496 in the future? > >>>> >>>>   Initially the SoC runs at 800MHz with a voltage of 875mV set by the bootloaders. As kernel does not know the initial voltage, during regulator registration the framework considers the current voltage to be zero and tries to bring up the regulator to minimum supported voltage of 600mV. This causes the dip which might be of concern in SS parts where the voltage might be insufficient leading to silent reboots. >>>> That's an SoC-specific thing, the same regulator can be used with >>>> many different ones. We can't just assume it'll always be like this. >>>> I see the problem, but I believe this is not the correct solution >> Okay, As we had discussions on reading back the voltage & the generic >> DT property, do you suggest any other possible solutions here? > Due to the sudden influx of various IPQ SoCs on the mailing list lately > I have no idea if it concerned this one too, but at least one of them > was said not to use RPM for controlling the clocks. If that's the case, > I see no reason at all to use it for scaling the regulators, the PMIC > could be addressed directly over I2C as a normal device. You'd probably > want to keep VDD_[CM]X scaling through rpmpd, but it's easily done by > simply not registering the CX/MX registers as children of the I2C > regulator IC. IPQ9574 SoC has RPM and uses it for controlling the regulators. Currently, the RPM firmware does not have read support implemented and so, we were not able to read the bootup voltage. As we randomly saw silent reboots when the kernel boots up, do you think we could proceed with this change for time being and revisit the same when any SoC in the future employs MP5496? > > Konrad >>>> >>>> Konrad >>>>> >>>>> Best Regards, >>>>> Devi Priya