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 24ADDC4332F for ; Wed, 9 Nov 2022 23:47:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231712AbiKIXrd (ORCPT ); Wed, 9 Nov 2022 18:47:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229806AbiKIXr3 (ORCPT ); Wed, 9 Nov 2022 18:47:29 -0500 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFFF91277B; Wed, 9 Nov 2022 15:47:28 -0800 (PST) Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2A9Nfg0Q003561; Wed, 9 Nov 2022 23:47:21 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=8z6ePNURMRjxd7MtLxb/FSdAdPRY7ppEWaO03gWnvWM=; b=Se7hIpnxcGbp6o55s/JLIRA9pg+PEqh3p8zKhi8C4xZANxY1PzjbXpVXk38f9rlPvn7H AR+zzhW2FK1o7DB66itmsZW2B5hQrhH3RPJAopmYSTWOzbV9Mbth0lvKRj6E6PWCc3QP eJG4/U4AhZ10DwBm0lEzyuCve/6SF2Ix5/FoTKYy9MXfUnjBbaokDREZAETggZFEBjM/ 8565RLbxAQ9FJnh/fV9MmYXU1bB5F/N/aziEtLqVQp9xwVERI3ZeZ1M0OaXRDIWGPmWC g8GhBwGIjjybLUdt3Ardhlb7J5eg5D+vVnOJ5HlHYy72g6slGWEHSJ/pC8+7v5+g8Ng9 8Q== Received: from nalasppmta03.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3krg2q900b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 09 Nov 2022 23:47:21 +0000 Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA03.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 2A9NlKvC023503 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 9 Nov 2022 23:47:20 GMT Received: from [10.110.62.155] (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 15.2.986.29; Wed, 9 Nov 2022 15:47:19 -0800 Message-ID: Date: Wed, 9 Nov 2022 15:47:18 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.4.0 Subject: Re: [PATCH] drm/msm/dp: remove limitation of link rate at 5.4G to support HBR3 Content-Language: en-US To: Dmitry Baryshkov , Doug Anderson CC: , , , , , , , , , , , , , Bjorn Andersson References: <1667237245-24988-1-git-send-email-quic_khsieh@quicinc.com> <94b507e8-5b94-12ae-4c81-95f5d36279d5@linaro.org> <155e4171-187c-4ecf-5a9b-12f0c2207524@linaro.org> <60643572-4148-cea5-e64d-ec6534b0c407@linaro.org> From: Kuogee Hsieh In-Reply-To: <60643572-4148-cea5-e64d-ec6534b0c407@linaro.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit 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-ORIG-GUID: HutC2z3yT8RN_6bXhyEjUefMrOqIVQEo X-Proofpoint-GUID: HutC2z3yT8RN_6bXhyEjUefMrOqIVQEo X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-09_06,2022-11-09_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 clxscore=1011 phishscore=0 adultscore=0 spamscore=0 bulkscore=0 mlxlogscore=891 lowpriorityscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211090179 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/2/2022 11:04 AM, Dmitry Baryshkov wrote: > On 02/11/2022 20:28, Doug Anderson wrote: >> Hi, >> >> On Wed, Nov 2, 2022 at 10:23 AM Dmitry Baryshkov >> wrote: >>> >>>> 1. Someone figures out how to model this with the bridge chain and >>>> then we only allow HBR3 if we detect we've got a TCPC that supports >>>> it. This seems like the cleanest / best but feels like a long pole. >>>> Not only have we been trying to get the TCPC-modeled-as-a-bridge stuff >>>> landed for a long time but even when we do it we still don't have a >>>> solution for how to communicate the number of lanes and other stuff >>>> between the TCPC and the DP controller so we have to enrich the bridge >>>> interface. >>> >>> I think we'd need some OOB interface. For example for DSI interfaces we >>> have mipi_dsi_device struct to communicate such OOB data. >>> >>> Also take a note regarding data-lanes from my previous email. >> >> Right, we can somehow communicate the max link rate through the bridge >> chain to the DP controller in an OOB manner that would work. > > I'd note that our dp_panel has some notion of such OOB data. So do AUX > drivers including the panel-edp. My suggestion would be to consider > both of them while modelling the OOB data. > >> >> >>>> 2. We add in a DT property to the display controller node that says >>>> the max link rate for use on this board. This feels like a hack, but >>>> maybe it's not too bad. Certainly it would be incredibly simple to >>>> implement. Actually... ...one could argue that even if we later model >>>> the TCPC as a bridge that this property would still be valid / useful! >>>> You could certainly imagine that the SoC supports HBR3 and the TCPC >>>> supports HBR3 but that the board routing between the SoC and the TCPC >>>> is bad and only supports HBR2. In this case the only way out is >>>> essentially a "board constraint" AKA a DT property in the DP >>>> controller. >>> >>> We have been discussing similar topics with Abhinav. Krzysztof >>> suggested >>> using link-frequencies property to provide max and min values. questions, 1)is Krzysztof suggested had been implemented? 2) where is link property i can add link-frequencies? >> >> This sounds good to me and seems worth doing even if we eventually do >> #1. > > And the bonus point is that it can be done easily. >