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 X-Spam-Level: X-Spam-Status: No, score=-5.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22E63C5DF60 for ; Fri, 8 Nov 2019 02:03:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5E0321882 for ; Fri, 8 Nov 2019 02:03:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="IgoQ4CLe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726556AbfKHCDf (ORCPT ); Thu, 7 Nov 2019 21:03:35 -0500 Received: from mail-il1-f193.google.com ([209.85.166.193]:33292 "EHLO mail-il1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725940AbfKHCDf (ORCPT ); Thu, 7 Nov 2019 21:03:35 -0500 Received: by mail-il1-f193.google.com with SMTP id m5so3739601ilq.0 for ; Thu, 07 Nov 2019 18:03:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rb7E4G3AfRv3BBvojQNjoB9UPjH1AyXc4p/SxsSL9W4=; b=IgoQ4CLeR5KSemdl8EH4Mv7SW5YfL/GAg/l1KhpuG8A/axs8uQnarKuxoDx6hd6iQG FsKC8qZR8md/Xc/sMEb0TgU7cYRUSq3Kg1zNXn2/d9L4Nn8slVxXisf0nqJOJxShSe27 9t2/w72HYCsTpM0ziXzT+tLqJOigzV/O34KlU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rb7E4G3AfRv3BBvojQNjoB9UPjH1AyXc4p/SxsSL9W4=; b=NipKBPdNicCGfjevC3TcIODiee5n1kK+4txM830IZ2ND2GUTGLSkmNHgulTSX0HjH0 OA6Zb2JicY1XUcT7mTRSBDx86oKc7Yin0g6sxTXfMDSJRxiSYXRqK2O0k6AuJPN1P1ee XOItkWER9PGlDhHwAnHke7bMZh9Yw+BSKrsYDMObNkXVfvCMZJYgqqroGdXdO+xtiLa+ pQQjKvWi0EQF5BuWqEuDvZqKwKoHtK2hjhzQn15wjWpQNk87dw4oTvW8iEj4AIj+YxjH waNU4MyztFT4bpnMafo1RjvOjl5RPc+nirjnLB8nZOD2pUQ/3DshLzihtCSdUZjCLuWu IVxA== X-Gm-Message-State: APjAAAWIb+Ao+y9Hb4V/c+Anu3HaEyQliB6o4eWUScEIJ4Ti1g/nvniW 35x7WS5WPHccpGw6rj6Y4lrEHpbFLNpP+OUMSW7/Ko1WpKM= X-Google-Smtp-Source: APXvYqwfvE0lbSsmo3rLw5QoJ6zVMyT9Wrt/mQAmklzCszTTgckYnb+UZs7Y5ORM7LCKGmCVLHGnxLClJWkwQGTwBOI= X-Received: by 2002:a92:c9c3:: with SMTP id k3mr9000230ilq.299.1573178614360; Thu, 07 Nov 2019 18:03:34 -0800 (PST) MIME-Version: 1.0 References: <20191105000129.GA6536@onstation.org> <20191105100804.GA9492@onstation.org> <20191106091335.GA16729@onstation.org> <20191107111019.GA24028@onstation.org> In-Reply-To: From: Rob Clark Date: Thu, 7 Nov 2019 18:03:24 -0800 Message-ID: Subject: Re: [Freedreno] drm/msm: 'pp done time out' errors after async commit changes To: Jeffrey Hugo Cc: Rob Clark , Brian Masney , freedreno , Linux Kernel Mailing List , dri-devel , linux-arm-msm , Sean Paul Content-Type: text/plain; charset="UTF-8" Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, Nov 7, 2019 at 9:40 AM Jeffrey Hugo wrote: > > On Thu, Nov 7, 2019 at 9:17 AM Rob Clark wrote: > > > > On Thu, Nov 7, 2019 at 3:10 AM Brian Masney wrote: > > > > > > On Wed, Nov 06, 2019 at 08:58:59AM -0800, Rob Clark wrote: > > > > On Wed, Nov 6, 2019 at 8:47 AM Jeffrey Hugo wrote: > > > > > > > > > > On Wed, Nov 6, 2019 at 9:30 AM Rob Clark wrote: > > > > > > > > > > > > On Wed, Nov 6, 2019 at 1:13 AM Brian Masney wrote: > > > > > > > > > > > > > > On Tue, Nov 05, 2019 at 08:23:27AM -0800, Rob Clark wrote: > > > > > > > > On Tue, Nov 5, 2019 at 2:08 AM Brian Masney wrote: > > > > > > > > > The 'pp done time out' errors go away if I revert the following three > > > > > > > > > commits: > > > > > > > > > > > > > > > > > > cd6d923167b1 ("drm/msm/dpu: async commit support") > > > > > > > > > d934a712c5e6 ("drm/msm: add atomic traces") > > > > > > > > > 2d99ced787e3 ("drm/msm: async commit support") > > > > > > > > > > > > > > > > > > I reverted the first one to fix a compiler error, and the second one so > > > > > > > > > that the last patch can be reverted without any merge conflicts. > > > > > > > > > > > > > > > > > > I see that crtc_flush() calls mdp5_ctl_commit(). I tried to use > > > > > > > > > crtc_flush_all() in mdp5_flush_commit() and the contents of the frame > > > > > > > > > buffer dance around the screen like its out of sync. I renamed > > > > > > > > > crtc_flush_all() to mdp5_crtc_flush_all() and removed the static > > > > > > > > > declaration. Here's the relevant part of what I tried: > > > > > > > > > > > > > > > > > > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c > > > > > > > > > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c > > > > > > > > > @@ -171,7 +171,15 @@ static void mdp5_prepare_commit(struct msm_kms *kms, struct drm_atomic_state *st > > > > > > > > > > > > > > > > > > static void mdp5_flush_commit(struct msm_kms *kms, unsigned crtc_mask) > > > > > > > > > { > > > > > > > > > - /* TODO */ > > > > > > > > > + struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(kms)); > > > > > > > > > + struct drm_crtc *crtc; > > > > > > > > > + > > > > > > > > > + for_each_crtc_mask(mdp5_kms->dev, crtc, crtc_mask) { > > > > > > > > > + if (!crtc->state->active) > > > > > > > > > + continue; > > > > > > > > > + > > > > > > > > > + mdp5_crtc_flush_all(crtc); > > > > > > > > > + } > > > > > > > > > } > > > > > > > > > > > > > > > > > > Any tips would be appreciated. > > > > > > > > > > > > > > > > > > > > > > > > I think this is along the lines of what we need to enable async commit > > > > > > > > for mdp5 (but also removing the flush from the atomic-commit path).. > > > > > > > > the principle behind the async commit is to do all the atomic state > > > > > > > > commit normally, but defer writing the flush bits. This way, if you > > > > > > > > get another async update before the next vblank, you just apply it > > > > > > > > immediately instead of waiting for vblank. > > > > > > > > > > > > > > > > But I guess you are on a command mode panel, if I remember? Which is > > > > > > > > a case I didn't have a way to test. And I'm not entirely about how > > > > > > > > kms_funcs->vsync_time() should be implemented for cmd mode panels. > > > > > > > > > > > > > > Yes, this is a command-mode panel and there's no hardware frame counter > > > > > > > available. The key to getting the display working on this phone was this > > > > > > > patch: > > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2bab52af6fe68c43b327a57e5ce5fc10eefdfadf > > > > > > > > > > > > > > > That all said, I think we should first fix what is broken, before > > > > > > > > worrying about extending async commit support to mdp5.. which > > > > > > > > shouldn't hit the async==true path, due to not implementing > > > > > > > > kms_funcs->vsync_time(). > > > > > > > > > > > > > > > > What I think is going on is that, in the cmd mode case, > > > > > > > > mdp5_wait_flush() (indirectly) calls mdp5_crtc_wait_for_pp_done(), > > > > > > > > which waits for a pp-done irq regardless of whether there is a flush > > > > > > > > in progress. Since there is no flush pending, the irq never comes. > > > > > > > > But the expectation is that kms_funcs->wait_flush() returns > > > > > > > > immediately if there is nothing to wait for. > > > > > > > > > > > > > > I don't think that's happening in this case. I added some pr_info() > > > > > > > statements to request_pp_done_pending() and mdp5_crtc_pp_done_irq(). > > > > > > > Here's the first two sets of messages that appear in dmesg: > > > > > > > > > > > > > > [ 14.018907] msm fd900000.mdss: pp done time out, lm=0 > > > > > > > [ 14.018993] request_pp_done_pending: HERE > > > > > > > [ 14.074208] mdp5_crtc_pp_done_irq: HERE > > > > > > > [ 14.074368] Console: switching to colour frame buffer device 135x120 > > > > > > > [ 14.138938] msm fd900000.mdss: pp done time out, lm=0 > > > > > > > [ 14.139021] request_pp_done_pending: HERE > > > > > > > [ 14.158097] mdp5_crtc_pp_done_irq: HERE > > > > > > > > > > > > > > The messages go on like this with the same pattern. > > > > > > > > > > > > > > I tried two different changes: > > > > > > > > > > > > > > 1) I moved the request_pp_done_pending() and corresponding if statement > > > > > > > from mdp5_crtc_atomic_flush() and into mdp5_crtc_atomic_begin(). > > > > > > > > > > > > > > 2) I increased the timeout in wait_for_completion_timeout() by several > > > > > > > increments; all the way to 5 seconds. > > > > > > > > > > > > increasing the timeout won't help, because the pp-done irq has already > > > > > > come at the point where we wait for it.. > > > > > > > > > > > > maybe the easy thing is just add mdp5_crtc->needs_pp, set to true > > > > > > before requesting, and false when we get the irq.. and then > > > > > > mdp5_crtc_wait_for_pp_done() just returns if needs_pp==false.. > > > > > > > > > > On the otherhand, what about trying to make command mode panels > > > > > resemble video mode panels slightly? Video mode panels have a vsync > > > > > counter in hardware, which is missing from command mode - however it > > > > > seems like the driver/drm framework would prefer such a counter. > > > > > Would it be a reasonable idea to make a software counter, and just > > > > > increment it every time the pp_done irq is triggered? > > > > > > > > > > I'm just thinking that we'll avoid issues long term by trying to make > > > > > the code common, rather than diverging it for the two modes. > > > > > > > > > > > > > *possibly*, but I think we want to account somehow periods where > > > > display is not updated. > > > > > > > > fwiw, it isn't that uncommon for userspace to use vblanks to "keep > > > > time" (drive animations for desktop switch, window > > > > maximize/unmaximize, etc).. it could be a surprise when "vblank" is > > > > not periodic. > > > > > > What do you think about using some variation of the current value of > > > jiffies in the kernel + the number of pp_done IRQs as the software > > > counter for command-mode panels? > > > > > > > jiffies is probably too coarse.. but we could use monotonic clock, I guess. > > > > But I suppose even a cmd mode panel has a "vblank", it is just > > internal the panel. Do we get the TE interrupt at regular intervals? > > AFAIU this would be tied to the panel's internal vblank. > > The TE interrupt was first implemented in MDP 1.7.0 (msm8996). 8974 > predates that. > You can get it from the WR_PTR interrupt, but you have to understand > details about your panel to configure that correctly. oh, sad.. I kinda assumed it was a pretty common DSI irq since forever.. I guess the hw is just managing the flow control to prevent tearing? Well, anyways, I guess we could just use a free-running timer based on refresh rate of the panel? BR, -R