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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 392CCC46460 for ; Wed, 29 May 2019 09:41:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13D30216FD for ; Wed, 29 May 2019 09:41:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=onstation.org header.i=@onstation.org header.b="uDwKDHPw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726601AbfE2Jly (ORCPT ); Wed, 29 May 2019 05:41:54 -0400 Received: from onstation.org ([52.200.56.107]:42284 "EHLO onstation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725874AbfE2Jly (ORCPT ); Wed, 29 May 2019 05:41:54 -0400 Received: from localhost (c-98-239-145-235.hsd1.wv.comcast.net [98.239.145.235]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: masneyb) by onstation.org (Postfix) with ESMTPSA id 9808F3E80A; Wed, 29 May 2019 09:41:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=onstation.org; s=default; t=1559122913; bh=fAIT6Gqdt//3ui/hAaGpZ95WCJf2S6gz5J7z91LX3xU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uDwKDHPwA+58QqCzC0Rg04rxThkFy0yaNMhRG8AOoQTAMbnuw/G+EH8RYfMhlJ/Tl My9ZVW4LkMPkxL0I/L8wkMl0ZHEwT6cIPFfZXuh5DfzDM+dYTmGaJ7rdL1hF+63oXo XTWXWh0Z+N/0W3PuP3A7PWdxXpTsnbRpSdtZq3Xs= Date: Wed, 29 May 2019 05:41:52 -0400 From: Brian Masney To: Linus Walleij Cc: Rob Clark , Sean Paul , "open list:DRM PANEL DRIVERS" , MSM , freedreno@lists.freedesktop.org, Dave Airlie , Daniel Vetter , "linux-kernel@vger.kernel.org" , Jonathan Marek , Rob Herring Subject: Re: [PATCH RFC v2 0/6] ARM: qcom: initial Nexus 5 display support Message-ID: <20190529094152.GB13436@basecamp> References: <20190509020352.14282-1-masneyb@onstation.org> <20190529011705.GA12977@basecamp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 29, 2019 at 08:23:17AM +0200, Linus Walleij wrote: > On Wed, May 29, 2019 at 3:17 AM Brian Masney wrote: > > > It's in low speed mode but its usable. > > How low speed is that? I don't have a number but my test with 4.17 is to run 'cat /etc/passwd > /dev/tty1' over a serial cable. The first 2-3 calls will fill up the screen and the file contents appear to show up on the screen immediately to the human eye. The next time that I run it requires scrolling the entire console and there is a small fraction of a second where I see the entire framebuffer contents scroll up. I don't have a graphics background, but I believe that this is the tearing effect that I'm seeing based on what I've read. I believe that disp-te-gpios can be used to mitigate this tearing effect. I have a few questions about this later once we get the basic display working. > > I assume that it's related to the > > vblank events not working properly? > > They are only waiting for 50 ms before timing out, I raised it > to 100ms in the -next kernel. I'm still suspicious about this > even though I think you said this was not the problem. > > For a command mode panel in LP mode it will nevertheless > be more than 100ms for sure, the update is visible to the > naked eye. > > Raise it to 10000 ms or something and see what happens. > drivers/gpu/drm/drm_atomic_helper.c: > msecs_to_jiffies(50) I previously raised those timeouts as high as 5 seconds and it still has the same issue. Writing to /dev/tty1 can take anywhere between a few seconds to 30 seconds or more. Brian