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 371F2C433FE for ; Tue, 26 Apr 2022 21:11:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355274AbiDZVOo (ORCPT ); Tue, 26 Apr 2022 17:14:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355272AbiDZVOo (ORCPT ); Tue, 26 Apr 2022 17:14:44 -0400 Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F5E475620; Tue, 26 Apr 2022 14:11:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1651007496; x=1682543496; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=qSK6NstQoSovqsAIqosH6BB7L0h+eEq9PVg+8PfxUjs=; b=Ng4+89CFkclAR+J4A3kEX9iLTRhyXxq9QvVpEVxQs5F91/TM0EA8KBo3 AiRUPs1puDqOLIPTDFRa9ZoVo/keTKpxPu5Gww26cx1LBfrs0QwGuLQJg v94TUif6pGVcjBsPCWwGyx0kOm5daE24M12y+unm5+mENRf9Cb6iZ2owp U=; Received: from ironmsg08-lv.qualcomm.com ([10.47.202.152]) by alexa-out.qualcomm.com with ESMTP; 26 Apr 2022 14:11:35 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg08-lv.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Apr 2022 14:11:35 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Tue, 26 Apr 2022 14:11:34 -0700 Received: from [10.111.160.161] (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 15.2.986.22; Tue, 26 Apr 2022 14:11:32 -0700 Message-ID: <37b16e86-f726-bf26-98ba-6146b6835c04@quicinc.com> Date: Tue, 26 Apr 2022 14:11:29 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH 2/2] drm/probe-helper: For DP, add 640x480 if all other modes are bad Content-Language: en-US To: Doug Anderson CC: Sankeerth Billakanti , David Airlie , linux-arm-msm , LKML , dri-devel , "Kuogee Hsieh (QUIC)" , Thomas Zimmermann , Dmitry Baryshkov , "Aravind Venkateswaran (QUIC)" , Stephen Boyd References: <20220426114627.1.I2dd93486c6952bd52f2020904de0133970d11b29@changeid> <20220426114627.2.I4ac7f55aa446699f8c200a23c10463256f6f439f@changeid> <517f71e4-785f-ef6f-d30e-fb18974eed57@quicinc.com> From: Abhinav Kumar In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 4/26/2022 1:26 PM, Doug Anderson wrote: > Hi, > > On Tue, Apr 26, 2022 at 12:20 PM Abhinav Kumar > wrote: >> >> Missed one more comment. >> >> On 4/26/2022 12:16 PM, Abhinav Kumar wrote: >>> Hi Doug >>> >>> One minor comment below. >>> >>> But otherwise, looking at this change this should work for us acc to me. >>> >>> We will test this out with our equipment and then provide R-b. >>> >>> Thanks >>> >>> Abhinav >>> On 4/26/2022 11:46 AM, Douglas Anderson wrote: >>>> As per Displayport spec section 5.2.1.2 ("Video Timing Format") says >>>> that all detachable sinks shall support 640x480 @60Hz as a fail safe >>>> mode. >>>> >>>> A DP compliance test expected us to utilize the above fact when all >>>> modes it presented to the DP source were not achievable. It presented >>>> only modes that would be achievable with more lanes and/or higher >>>> speeds than we had available and expected that when we couldn't do >>>> that then we'd fall back to 640x480 even though it didn't advertise >>>> this size. >>>> >>>> In order to pass the compliance test (and also support any users who >>>> might fall into a similar situation with their display), we need to >>>> add 640x480 into the list of modes. However, we don't want to add >>>> 640x480 all the time. Despite the fact that the DP spec says all sinks >>>> _shall support_ 640x480, they're not guaranteed to support it >>>> _well_. Continuing to read the spec you can see that the display is >>>> not required to really treat 640x480 equal to all the other modes. It >>>> doesn't need to scale or anything--just display the pixels somehow for >>>> failsafe purposes. It should also be noted that it's not hard to find >>>> a display hooked up via DisplayPort that _doesn't_ support 640x480 at >>>> all. The HP ZR30w screen I'm sitting in front of has a native DP port >>>> and doesn't work at 640x480. I also plugged in a tiny 800x480 HDMI >>>> display via a DP to HDMI adapter and that screen definitely doesn't >>>> support 640x480. >>>> >>>> As a compromise solution, let's only add the 640x480 mode if: >>>> * We're on DP. >>>> * All other modes have been pruned. >>>> >>>> This acknowledges that 640x480 might not be the best mode to use but, >>>> since sinks are _supposed_ to support it, we will at least fall back >>>> to it if there's nothing else. >>>> >>>> Note that we _don't_ add higher resolution modes like 1024x768 in this >>>> case. We only add those modes for a failed EDID read where we have no >>>> idea what's going on. In the case where we've pruned all modes then >>>> instead we only want 640x480 which is the only defined "Fail Safe" >>>> resolution. >>>> >>>> This patch originated in response to Kuogee Hsieh's patch [1]. >>>> >>>> [1] >>>> https://lore.kernel.org/r/1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com >>>> >>>> >>>> Signed-off-by: Douglas Anderson >>>> --- >>>> >>>> drivers/gpu/drm/drm_probe_helper.c | 26 +++++++++++++++++++++----- >>>> 1 file changed, 21 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_probe_helper.c >>>> b/drivers/gpu/drm/drm_probe_helper.c >>>> index 819225629010..90cd46cbfec1 100644 >>>> --- a/drivers/gpu/drm/drm_probe_helper.c >>>> +++ b/drivers/gpu/drm/drm_probe_helper.c >>>> @@ -476,7 +476,6 @@ int drm_helper_probe_single_connector_modes(struct >>>> drm_connector *connector, >>>> const struct drm_connector_helper_funcs *connector_funcs = >>>> connector->helper_private; >>>> int count = 0, ret; >>>> - bool verbose_prune = true; >>>> enum drm_connector_status old_status; >>>> struct drm_modeset_acquire_ctx ctx; >>>> @@ -556,8 +555,8 @@ int drm_helper_probe_single_connector_modes(struct >>>> drm_connector *connector, >>>> DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n", >>>> connector->base.id, connector->name); >>>> drm_connector_update_edid_property(connector, NULL); >>>> - verbose_prune = false; >>>> - goto prune; >>>> + drm_mode_prune_invalid(dev, &connector->modes, false); >>>> + goto exit; >>>> } >>>> count = (*connector_funcs->get_modes)(connector); >>>> @@ -580,9 +579,26 @@ int >>>> drm_helper_probe_single_connector_modes(struct drm_connector *connector, >>>> } >>>> } >>>> -prune: >>>> - drm_mode_prune_invalid(dev, &connector->modes, verbose_prune); >>>> + drm_mode_prune_invalid(dev, &connector->modes, true); >>>> + /* >>>> + * Displayport spec section 5.2.1.2 ("Video Timing Format") says >>>> that >>>> + * all detachable sinks shall support 640x480 @60Hz as a fail safe >>>> + * mode. If all modes were pruned, perhaps because they need more >>>> + * lanes or a higher pixel clock than available, at least try to add >>>> + * in 640x480. >>>> + */ >>>> + if (list_empty(&connector->modes) && >>>> + connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) { >>>> + count = drm_add_modes_noedid(connector, 640, 480); >>>> + if (_drm_helper_update_and_validate(connector, maxX, maxY, >>>> &ctx)) { >>>> + drm_modeset_backoff(&ctx); >>>> + goto retry; >>> >>> Do we need another retry here? This will again repeat everything from >>> get_modes(). >>> The fact that we are hitting this code is because we have already tried >>> that and this is already a second-pass. So I think another retry isnt >>> needed? >> >> This will help cover the case of 4.2.2.6 but not fix 4.2.2.1. >> >> For 4.2.2.1, we will have 0 modes and so the original DRM fwk code of >> adding all modes <= 1024x768 will kick in. >> >> Now, in that list, we will still need to pick/mark 640x480 as the >> preferred mode. >> >> We still need IGT for that. > > Are you sure you don't have those backwards? It seems like 4.2.2.6 is > the test case dealing with corrupt EDID and that's the one that will > still be broken, no? ...and corrupt EDID is still the case where we > have 0 modes. Yes indeed, sorry, I did have the numbers backwards. 4.2.2.6 will still be broken. > > In any case, let's see what people think about: > > https://lore.kernel.org/r/20220426132121.RFC.1.I31ec454f8d4ffce51a7708a8092f8a6f9c929092@changeid Yes sure. If it gets accepted, it will save us some IGT work. > > I've marked that one as RFC just because it seems like a bigger change > to existing behavior, though it still seems correct to me. > > NOTE: reading 4.2.2.6 more closely, it actually looks as if we're > actually supposed to be able to try various video modes one at a time > until we find one that works (or land on 640x480). Seems as if we're > supposed to be able to try the higher resolutions one at a time and we > can tell whether the sink "accepted" it by seeing if SINK_STATUS goes > to 1? I have no idea how that works with all the Linux APIs, though. > hmmm .... our equipment throws a warning if we dont sent 640x480. So perhaps just go with the "or land on 640x480" option. 0006.392.232: [WARNING] Source DUT failed to transmit a video stream using fail-safe mode 0006.392.491: Received 1344 Htotal differs from fail-safe 800 0006.392.621: Received 1024 Hactive differs from fail-safe 640 0006.392.750: Received 296 Hstart differs from fail-safe 144 0006.392.868: Received 136 Hsync width differs from fail-safe 96 0006.392.975: Received 806 Vtotal differs from fail-safe 525 0006.393.099: Received 768 Vactive differs from fail-safe 480 0006.393.229: Received 6 Vsync width differs from fail-safe 2 > -Doug 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 94245C433F5 for ; Tue, 26 Apr 2022 21:11:37 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E40D510E708; Tue, 26 Apr 2022 21:11:36 +0000 (UTC) Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by gabe.freedesktop.org (Postfix) with ESMTPS id C9CB010E708 for ; Tue, 26 Apr 2022 21:11:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1651007496; x=1682543496; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=qSK6NstQoSovqsAIqosH6BB7L0h+eEq9PVg+8PfxUjs=; b=Ng4+89CFkclAR+J4A3kEX9iLTRhyXxq9QvVpEVxQs5F91/TM0EA8KBo3 AiRUPs1puDqOLIPTDFRa9ZoVo/keTKpxPu5Gww26cx1LBfrs0QwGuLQJg v94TUif6pGVcjBsPCWwGyx0kOm5daE24M12y+unm5+mENRf9Cb6iZ2owp U=; Received: from ironmsg08-lv.qualcomm.com ([10.47.202.152]) by alexa-out.qualcomm.com with ESMTP; 26 Apr 2022 14:11:35 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg08-lv.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Apr 2022 14:11:35 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Tue, 26 Apr 2022 14:11:34 -0700 Received: from [10.111.160.161] (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 15.2.986.22; Tue, 26 Apr 2022 14:11:32 -0700 Message-ID: <37b16e86-f726-bf26-98ba-6146b6835c04@quicinc.com> Date: Tue, 26 Apr 2022 14:11:29 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH 2/2] drm/probe-helper: For DP, add 640x480 if all other modes are bad Content-Language: en-US To: Doug Anderson References: <20220426114627.1.I2dd93486c6952bd52f2020904de0133970d11b29@changeid> <20220426114627.2.I4ac7f55aa446699f8c200a23c10463256f6f439f@changeid> <517f71e4-785f-ef6f-d30e-fb18974eed57@quicinc.com> From: Abhinav Kumar In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sankeerth Billakanti , David Airlie , linux-arm-msm , LKML , dri-devel , "Kuogee Hsieh \(QUIC\)" , Thomas Zimmermann , Dmitry Baryshkov , "Aravind Venkateswaran \(QUIC\)" , Stephen Boyd Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 4/26/2022 1:26 PM, Doug Anderson wrote: > Hi, > > On Tue, Apr 26, 2022 at 12:20 PM Abhinav Kumar > wrote: >> >> Missed one more comment. >> >> On 4/26/2022 12:16 PM, Abhinav Kumar wrote: >>> Hi Doug >>> >>> One minor comment below. >>> >>> But otherwise, looking at this change this should work for us acc to me. >>> >>> We will test this out with our equipment and then provide R-b. >>> >>> Thanks >>> >>> Abhinav >>> On 4/26/2022 11:46 AM, Douglas Anderson wrote: >>>> As per Displayport spec section 5.2.1.2 ("Video Timing Format") says >>>> that all detachable sinks shall support 640x480 @60Hz as a fail safe >>>> mode. >>>> >>>> A DP compliance test expected us to utilize the above fact when all >>>> modes it presented to the DP source were not achievable. It presented >>>> only modes that would be achievable with more lanes and/or higher >>>> speeds than we had available and expected that when we couldn't do >>>> that then we'd fall back to 640x480 even though it didn't advertise >>>> this size. >>>> >>>> In order to pass the compliance test (and also support any users who >>>> might fall into a similar situation with their display), we need to >>>> add 640x480 into the list of modes. However, we don't want to add >>>> 640x480 all the time. Despite the fact that the DP spec says all sinks >>>> _shall support_ 640x480, they're not guaranteed to support it >>>> _well_. Continuing to read the spec you can see that the display is >>>> not required to really treat 640x480 equal to all the other modes. It >>>> doesn't need to scale or anything--just display the pixels somehow for >>>> failsafe purposes. It should also be noted that it's not hard to find >>>> a display hooked up via DisplayPort that _doesn't_ support 640x480 at >>>> all. The HP ZR30w screen I'm sitting in front of has a native DP port >>>> and doesn't work at 640x480. I also plugged in a tiny 800x480 HDMI >>>> display via a DP to HDMI adapter and that screen definitely doesn't >>>> support 640x480. >>>> >>>> As a compromise solution, let's only add the 640x480 mode if: >>>> * We're on DP. >>>> * All other modes have been pruned. >>>> >>>> This acknowledges that 640x480 might not be the best mode to use but, >>>> since sinks are _supposed_ to support it, we will at least fall back >>>> to it if there's nothing else. >>>> >>>> Note that we _don't_ add higher resolution modes like 1024x768 in this >>>> case. We only add those modes for a failed EDID read where we have no >>>> idea what's going on. In the case where we've pruned all modes then >>>> instead we only want 640x480 which is the only defined "Fail Safe" >>>> resolution. >>>> >>>> This patch originated in response to Kuogee Hsieh's patch [1]. >>>> >>>> [1] >>>> https://lore.kernel.org/r/1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com >>>> >>>> >>>> Signed-off-by: Douglas Anderson >>>> --- >>>> >>>> drivers/gpu/drm/drm_probe_helper.c | 26 +++++++++++++++++++++----- >>>> 1 file changed, 21 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_probe_helper.c >>>> b/drivers/gpu/drm/drm_probe_helper.c >>>> index 819225629010..90cd46cbfec1 100644 >>>> --- a/drivers/gpu/drm/drm_probe_helper.c >>>> +++ b/drivers/gpu/drm/drm_probe_helper.c >>>> @@ -476,7 +476,6 @@ int drm_helper_probe_single_connector_modes(struct >>>> drm_connector *connector, >>>> const struct drm_connector_helper_funcs *connector_funcs = >>>> connector->helper_private; >>>> int count = 0, ret; >>>> - bool verbose_prune = true; >>>> enum drm_connector_status old_status; >>>> struct drm_modeset_acquire_ctx ctx; >>>> @@ -556,8 +555,8 @@ int drm_helper_probe_single_connector_modes(struct >>>> drm_connector *connector, >>>> DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n", >>>> connector->base.id, connector->name); >>>> drm_connector_update_edid_property(connector, NULL); >>>> - verbose_prune = false; >>>> - goto prune; >>>> + drm_mode_prune_invalid(dev, &connector->modes, false); >>>> + goto exit; >>>> } >>>> count = (*connector_funcs->get_modes)(connector); >>>> @@ -580,9 +579,26 @@ int >>>> drm_helper_probe_single_connector_modes(struct drm_connector *connector, >>>> } >>>> } >>>> -prune: >>>> - drm_mode_prune_invalid(dev, &connector->modes, verbose_prune); >>>> + drm_mode_prune_invalid(dev, &connector->modes, true); >>>> + /* >>>> + * Displayport spec section 5.2.1.2 ("Video Timing Format") says >>>> that >>>> + * all detachable sinks shall support 640x480 @60Hz as a fail safe >>>> + * mode. If all modes were pruned, perhaps because they need more >>>> + * lanes or a higher pixel clock than available, at least try to add >>>> + * in 640x480. >>>> + */ >>>> + if (list_empty(&connector->modes) && >>>> + connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) { >>>> + count = drm_add_modes_noedid(connector, 640, 480); >>>> + if (_drm_helper_update_and_validate(connector, maxX, maxY, >>>> &ctx)) { >>>> + drm_modeset_backoff(&ctx); >>>> + goto retry; >>> >>> Do we need another retry here? This will again repeat everything from >>> get_modes(). >>> The fact that we are hitting this code is because we have already tried >>> that and this is already a second-pass. So I think another retry isnt >>> needed? >> >> This will help cover the case of 4.2.2.6 but not fix 4.2.2.1. >> >> For 4.2.2.1, we will have 0 modes and so the original DRM fwk code of >> adding all modes <= 1024x768 will kick in. >> >> Now, in that list, we will still need to pick/mark 640x480 as the >> preferred mode. >> >> We still need IGT for that. > > Are you sure you don't have those backwards? It seems like 4.2.2.6 is > the test case dealing with corrupt EDID and that's the one that will > still be broken, no? ...and corrupt EDID is still the case where we > have 0 modes. Yes indeed, sorry, I did have the numbers backwards. 4.2.2.6 will still be broken. > > In any case, let's see what people think about: > > https://lore.kernel.org/r/20220426132121.RFC.1.I31ec454f8d4ffce51a7708a8092f8a6f9c929092@changeid Yes sure. If it gets accepted, it will save us some IGT work. > > I've marked that one as RFC just because it seems like a bigger change > to existing behavior, though it still seems correct to me. > > NOTE: reading 4.2.2.6 more closely, it actually looks as if we're > actually supposed to be able to try various video modes one at a time > until we find one that works (or land on 640x480). Seems as if we're > supposed to be able to try the higher resolutions one at a time and we > can tell whether the sink "accepted" it by seeing if SINK_STATUS goes > to 1? I have no idea how that works with all the Linux APIs, though. > hmmm .... our equipment throws a warning if we dont sent 640x480. So perhaps just go with the "or land on 640x480" option. 0006.392.232: [WARNING] Source DUT failed to transmit a video stream using fail-safe mode 0006.392.491: Received 1344 Htotal differs from fail-safe 800 0006.392.621: Received 1024 Hactive differs from fail-safe 640 0006.392.750: Received 296 Hstart differs from fail-safe 144 0006.392.868: Received 136 Hsync width differs from fail-safe 96 0006.392.975: Received 806 Vtotal differs from fail-safe 525 0006.393.099: Received 768 Vactive differs from fail-safe 480 0006.393.229: Received 6 Vsync width differs from fail-safe 2 > -Doug