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 957F1C7EE23 for ; Fri, 12 May 2023 00:17:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239638AbjELARJ (ORCPT ); Thu, 11 May 2023 20:17:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239624AbjELARE (ORCPT ); Thu, 11 May 2023 20:17:04 -0400 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D17A7271B; Thu, 11 May 2023 17:17:02 -0700 (PDT) Received: from pps.filterd (m0279869.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 34C0Gp5D030211; Fri, 12 May 2023 00:16:51 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=jSj+NhCwQKjZy4GYJIlA34ECE1KfkQwQTzcR7Ko1TyI=; b=YjxKrPbwEKfziIBfKwrZArch2ZTYryI2MvORjyoYPkH9iwKuaLe+yj9X4heQWPJnlzkV tfLruHMKOj9CfDTQaNf6npjNlDqIjlP2ruJdEJkUBthtAVWg3QWs2Sgw1mNtZpBKjiI6 Gge5nuf34u2QsSCldVELB5g088UB5ahsmLAsAaLzK81GSNZd85vOKhMxkMxq4T0VI5Rp sEodNdaoBin/f82a7Mb56tQ/vYG+VKGy5JsgHoL8VGvwuRGfIQL/JACv4u/KYFT2rVzA 5zFdQmfc4rKcFm6t5CaOk/fwYGWkvkA8E9xah7RCOGAqNPo0IWu0vXMW1so/dH+x8Gry Lg== Received: from nalasppmta03.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3qh24h14rb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 12 May 2023 00:16:51 +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 34C0GoKG008076 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 12 May 2023 00:16:50 GMT Received: from [10.110.12.203] (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 15.2.986.42; Thu, 11 May 2023 17:16:48 -0700 Message-ID: <8ac0b5f5-27da-2b28-8f10-b2fca447511a@quicinc.com> Date: Thu, 11 May 2023 17:16:48 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v1 1/2] drm/msm/dp: enable HDP plugin/unplugged interrupts to hpd_enable/disable Content-Language: en-US To: Dmitry Baryshkov , Bjorn Andersson CC: , , , , , , , , , , , , , , , References: <1683750665-8764-1-git-send-email-quic_khsieh@quicinc.com> <1683750665-8764-2-git-send-email-quic_khsieh@quicinc.com> <20230511155331.2jmfe7xcs5tihdgb@ripper> <5ef83699-01de-d062-6239-9bb834c70458@linaro.org> From: Kuogee Hsieh In-Reply-To: <5ef83699-01de-d062-6239-9bb834c70458@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: tdGTkWR988iNGxlCtpmtFJy7_L1naaGi X-Proofpoint-ORIG-GUID: tdGTkWR988iNGxlCtpmtFJy7_L1naaGi 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=2023-05-11_19,2023-05-05_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 adultscore=0 priorityscore=1501 phishscore=0 impostorscore=0 suspectscore=0 malwarescore=0 bulkscore=0 mlxscore=0 clxscore=1015 lowpriorityscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000 definitions=main-2305120000 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/11/2023 8:57 AM, Dmitry Baryshkov wrote: > On 11/05/2023 18:53, Bjorn Andersson wrote: >> On Thu, May 11, 2023 at 07:24:46AM +0300, Dmitry Baryshkov wrote: >>> On Wed, 10 May 2023 at 23:31, Kuogee Hsieh >>> wrote: >>>> >>>> The internal_hpd flag was introduced to handle external DP HPD >>>> derived from GPIO >>>> pinmuxed into DP controller. HPD plug/unplug interrupts cannot be >>>> enabled until >>>> internal_hpd flag is set to true. >>>> At both bootup and resume time, the DP driver will enable external DP >>>> plugin interrupts and handle plugin interrupt accordingly. >>>> Unfortunately >>>> dp_bridge_hpd_enable() bridge ops function was called to set >>>> internal_hpd >>>> flag to true later than where DP driver expected during bootup time. >>>> >>>> This causes external DP plugin event to not get detected and >>>> display stays blank. >>>> Move enabling HDP plugin/unplugged interrupts to >>>> dp_bridge_hpd_enable()/disable() to >>>> set internal_hpd to true along with enabling HPD plugin/unplugged >>>> interrupts >>>> simultaneously to avoid timing issue during bootup and resume. >>>> >>>> Fixes: cd198caddea7 ("drm/msm/dp: Rely on hpd_enable/disable >>>> callbacks") >>>> Signed-off-by: Kuogee Hsieh >>> >>> Thanks for debugging this! >>> >>> However after looking at the driver I think there is more than this. >>> >>> We have several other places gated on internal_hpd flag, where we do >>> not have a strict ordering of events. >>> I see that dp_hpd_plug_handle() and dp_hpd_unplug_handle() also toggle >>> DP_DP_IRQ_HPD_INT_MASK and DP_DP_HPD_REPLUG_INT_MASK depending on >>> internal_hpd. Can we toggle all 4 interrupts from the >>> hpd_enable/hpd_disable functions? If we can do it, then I think we can >>> drop the internal_hpd flag completely. >>> >> >> Yes, that's what I believe the DRM framework intend us to do. >> >> The problem, and reason why I didn't do tat in my series, was that in >> order to update the INT_MASKs you need to clock the IP-block and that's >> done elsewhere. >> >> So, for the internal_hpd case, it seems appropriate to pm_runtime_get() >> in hpd_enable() and unmask the HPD interrupts, and mask the interrupts >> and pm_runtime_put() in hpd_disable(). >> >> >> But for edp and external HPD-signal we also need to make sure power is >> on while something is connected... > > I think this is already handled by the existing code, see calls to the > dp_display_host_init(). > >> >>> I went on and checked other places where it is used: >>> - dp_hpd_unplug_handle(), guarding DP_DP_HPD_PLUG_INT_MASK toggling. I >>> think we can drop these two calls completely. The function is under >>> the event_mutex protection, so other events can not interfere. >>> - dp_bridge_hpd_notify(). What is the point of this check? If some >>> other party informs us of the HPD event, we'd better handle it instead >>> of dropping it. Correct?  In other words, I'd prefer seeing the >>> hpd_event_thread removal. Instead of that I think that on >>> HPD/plug/unplug/etc. IRQ the driver should call into the drm stack, >>> then the hpd_notify call should process those events. >>> 1) DP with GPIO: No downstream drm_bridge are connected, is_edp = false and internal HPD-logic is in used (internal_hpd = true). Power needs to be on at all times etc. 2) DP without GPIO: Downstream drm_bridge connected, is_edp = false and internal HPD-logic should not be used/enabled (internal_hpd = false). Power doesn't need to be on unless hpd_notify is invoked to tell us that there's something connected... - dp_bridge_hpd_notify(). What is the point of this check? <== i have below two questions, 1) can you explain when/what this dp_bridge_hpd_notify() will be called? 2) is dp_bridge_hpd_notify() only will be called at above case #2? and it will not be used by case #1? >> >> I agree, that seems to be what's expected of us from the DRM framework. >> >> Regards, >> Bjorn >> >>> >>>> --- >>>>   drivers/gpu/drm/msm/dp/dp_display.c | 27 ++++++++++++++------------- >>>>   1 file changed, 14 insertions(+), 13 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c >>>> b/drivers/gpu/drm/msm/dp/dp_display.c >>>> index 3e13acdf..71aa944 100644 >>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c >>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c >>>> @@ -1088,13 +1088,6 @@ static void dp_display_config_hpd(struct >>>> dp_display_private *dp) >>>>          dp_display_host_init(dp); >>>>          dp_catalog_ctrl_hpd_config(dp->catalog); >>>> >>>> -       /* Enable plug and unplug interrupts only if requested */ >>>> -       if (dp->dp_display.internal_hpd) >>>> -               dp_catalog_hpd_config_intr(dp->catalog, >>>> -                               DP_DP_HPD_PLUG_INT_MASK | >>>> -                               DP_DP_HPD_UNPLUG_INT_MASK, >>>> -                               true); >>>> - >>>>          /* Enable interrupt first time >>>>           * we are leaving dp clocks on during disconnect >>>>           * and never disable interrupt >>>> @@ -1396,12 +1389,6 @@ static int dp_pm_resume(struct device *dev) >>>> >>>>          dp_catalog_ctrl_hpd_config(dp->catalog); >>>> >>>> -       if (dp->dp_display.internal_hpd) >>>> -               dp_catalog_hpd_config_intr(dp->catalog, >>>> -                               DP_DP_HPD_PLUG_INT_MASK | >>>> -                               DP_DP_HPD_UNPLUG_INT_MASK, >>>> -                               true); >>>> - >>>>          if (dp_catalog_link_is_connected(dp->catalog)) { >>>>                  /* >>>>                   * set sink to normal operation mode -- D0 >>>> @@ -1801,15 +1788,29 @@ void dp_bridge_hpd_enable(struct drm_bridge >>>> *bridge) >>>>   { >>>>          struct msm_dp_bridge *dp_bridge = to_dp_bridge(bridge); >>>>          struct msm_dp *dp_display = dp_bridge->dp_display; >>>> +       struct dp_display_private *dp; >>>> + >>>> +       dp = container_of(dp_display, struct dp_display_private, >>>> dp_display); >>>> >>>>          dp_display->internal_hpd = true; >>>> +       dp_catalog_hpd_config_intr(dp->catalog, >>>> +                               DP_DP_HPD_PLUG_INT_MASK | >>>> +                               DP_DP_HPD_UNPLUG_INT_MASK, >>>> +                               true); >>>>   } >>>> >>>>   void dp_bridge_hpd_disable(struct drm_bridge *bridge) >>>>   { >>>>          struct msm_dp_bridge *dp_bridge = to_dp_bridge(bridge); >>>>          struct msm_dp *dp_display = dp_bridge->dp_display; >>>> +       struct dp_display_private *dp; >>>> + >>>> +       dp = container_of(dp_display, struct dp_display_private, >>>> dp_display); >>>> >>>> +       dp_catalog_hpd_config_intr(dp->catalog, >>>> +                               DP_DP_HPD_PLUG_INT_MASK | >>>> +                               DP_DP_HPD_UNPLUG_INT_MASK, >>>> +                               false); >>>>          dp_display->internal_hpd = false; >>>>   } >>> >>> -- >>> With best wishes >>> Dmitry >