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 34DDBCCA47F for ; Thu, 30 Jun 2022 02:10:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231334AbiF3CKb (ORCPT ); Wed, 29 Jun 2022 22:10:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229609AbiF3CKa (ORCPT ); Wed, 29 Jun 2022 22:10:30 -0400 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D5ED3DA58; Wed, 29 Jun 2022 19:10:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1656555029; x=1688091029; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=VkE1t8r/62tuKtjsziGoezRkG42VcXA8LP22e3VJDXo=; b=fg8RlwN7v39//Kk4u5MhIQii1RE+/h8i9stUQ9ngF97YD5CUzjV4tAuo mpzhqWRlM+mzIxp65h9jZOUTZZuUDC8+nCNkme/CPZwDeatFSyYk6XIPY +wQjQRREkQdt4TlqWrDMwFEeGNAcsFWlz/5Cto9zADqTmooUxmPlaC5AX g=; Received: from unknown (HELO ironmsg02-sd.qualcomm.com) ([10.53.140.142]) by alexa-out-sd-01.qualcomm.com with ESMTP; 29 Jun 2022 19:10:29 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg02-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jun 2022 19:10:27 -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; Wed, 29 Jun 2022 19:10:27 -0700 Received: from [10.38.245.159] (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; Wed, 29 Jun 2022 19:10:24 -0700 Message-ID: <537e8e8b-03f7-9fc0-4416-3b69d375ba9b@quicinc.com> Date: Wed, 29 Jun 2022 19:10:21 -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: [Freedreno] [PATCH] drm/msm/dp: make eDP panel as the first connected connector Content-Language: en-US To: Rob Clark , Doug Anderson CC: freedreno , Sankeerth Billakanti , David Airlie , "Kuogee Hsieh (QUIC)" , dri-devel , Stephen Boyd , "Vinod Koul" , Andy Gross , Daniel Vetter , linux-arm-msm , "Dmitry Baryshkov" , "Aravind Venkateswaran (QUIC)" , Bjorn Andersson , Sean Paul , LKML References: <1656429606-2765-1-git-send-email-quic_khsieh@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: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/29/2022 6:57 PM, Rob Clark wrote: > On Wed, Jun 29, 2022 at 5:36 PM Doug Anderson wrote: >> >> Hi, >> >> On Tue, Jun 28, 2022 at 1:14 PM Dmitry Baryshkov >> wrote: >>> >>> On 28 June 2022 18:20:06 GMT+03:00, Kuogee Hsieh wrote: >>>> Some userspace presumes that the first connected connector is the main >>>> display, where it's supposed to display e.g. the login screen. For >>>> laptops, this should be the main panel. >>>> >>>> This patch call drm_helper_move_panel_connectors_to_head() after >>>> drm_bridge_connector_init() to make sure eDP stay at head of >>>> connected connector list. This fixes unexpected corruption happen >>>> at eDP panel if eDP is not placed at head of connected connector >>>> list. >>> >>> The change itself is a good fix anyway. (And I'd ack it.) However I would like to understand why does it fix the corruption issue. What is we have eDP and DSI, with DSI ending up before the eDP? Would we see the issue? >>> Also could you please describe the mind of corruption you are observing? >> >> I've spent a whole bunch of time poking at this and in the end my >> conclusion is this: >> >> 1. The glitchyness seems to be a result of the Chrome OS userspace >> somehow telling the kernel to do something wrong. >> >> 2. I believe (though I have no proof other than Kuogee's patch fixing >> things) that the Chrome OS userspace is simply confused by the eDP >> connector being second. This would imply that Kuogee's patch is >> actually the right one. >> >> 3. It would be ideal if the Chrome OS userspace were fixed to handle >> this, but it's an area of code that I've never looked at. It also >> seems terribly low priority to fix since apparently other OSes have >> similar problems (seems like this code was originally added by >> RedHat?) >> >> >> Specifically, I tested with a similar but "persistent" glitch that I >> reproduced. The glitch Kuogee was digging into was a transitory glitch >> on the eDP (internal) display when you plugged in a DP (external) >> display. It would show up for a frame or two and then be fixed. I can >> get a similar-looking glitch (vertical black and white bars) that >> persists by doing these steps on a Chrome OS device (and Chrome OS >> kernel): >> >> a) Observe screen looks good. >> b) Observe DP not connected. >> c) Plug in DP >> d) See transitory glitch on screen, then it all looks fine. >> e) set_power_policy --ac_screen_dim_delay=5 --ac_screen_off_delay=10 >> f) Wait for screen to turn off >> g) Unplug DP >> h) Hit key on keyboard to wake device. >> i) See glitchy. >> j) Within 5 seconds: set_power_policy --ac_screen_dim_delay=5000 >> --ac_screen_off_delay=10000 >> >> Once I'm in the persistent glitch: >> >> * The "screenshot" command in Chrome OS shows corruption. Not exactly >> black and white bars, but the image produced has distinct bands of >> garbage. >> >> * I can actually toggle between VT2 and the main screen (VT1). Note >> that VT1/VT2 are not quite the normal Linux managed solution--I >> believe they're handled by frecon. In any case, when I switch to VT2 >> it looks normal (I can see the login prompt). Then back to VT1 and the >> vertical bars glitch. Back to VT2 and it's normal. Back to VT1 and the >> glitch again. This implies (especially with the extra evidence of >> screenshot) that the display controller hardware is all fine and that >> it's the underlying data that's somehow messed up. > > fwiw, from looking at this a bit w/ Doug, I think the "glitch" is > simply just an un-renderered buffer being interpreted by the display > controller as UBWC (because userspace tells it to) > > BR, > -R Acked and agree with the comments both of you have stated and looking at the corrupted buffers in the snapshot. Hence, Reviewed-by: Abhinav Kumar > >> When I pick Kuogee's patch then this "persistent" glitch goes away >> just like the transitory one does. >> >> I'm going to go ahead and do: >> >> Reviewed-by: Douglas Anderson >> Tested-by: Douglas Anderson