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 DACDDC433F5 for ; Wed, 11 May 2022 11:12:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234084AbiEKLMV (ORCPT ); Wed, 11 May 2022 07:12:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229534AbiEKLMT (ORCPT ); Wed, 11 May 2022 07:12:19 -0400 Received: from smtp1.de.adit-jv.com (smtp1.de.adit-jv.com [93.241.18.167]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39EC11DEC57; Wed, 11 May 2022 04:12:17 -0700 (PDT) Received: from hi2exch02.adit-jv.com (hi2exch02.adit-jv.com [10.72.92.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp1.de.adit-jv.com (Postfix) with ESMTPS id 7AC993C00BA; Wed, 11 May 2022 13:12:15 +0200 (CEST) Received: from lxhi-065 (10.72.94.33) by hi2exch02.adit-jv.com (10.72.92.28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2308.27; Wed, 11 May 2022 13:12:15 +0200 Date: Wed, 11 May 2022 13:12:10 +0200 From: Eugeniu Rosca To: , , Laurent Pinchart , Kieran Bingham CC: Koji Matsuoka , Michael Rodin , Eugen Friedrich , Eugeniu Rosca , Eugeniu Rosca Subject: Re: [RFC] media: renesas: vsp1: Add VSPD underrun detection & tracing Message-ID: <20220511111210.GA4369@lxhi-065> References: <1650962227-14281-1-git-send-email-erosca@de.adit-jv.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1650962227-14281-1-git-send-email-erosca@de.adit-jv.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Originating-IP: [10.72.94.33] X-ClientProxiedBy: hi2exch02.adit-jv.com (10.72.92.28) To hi2exch02.adit-jv.com (10.72.92.28) Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Dear Laurent, Dear Kieran, On Di, Apr 26, 2022 at 10:37:07 +0200, Eugeniu Rosca wrote: > A barely noticeable (especially if hardly reproducible) display flicker > may not be the biggest concern in the development environment. However, > an automotive OEM will not only notice it, but will also be haunted by > its phenomenon/nature till it is understood in the greatest detail and > ultimately eradicated, to avoid impairing user experience. > > Troubleshooting the above without the right tools becomes a nightmare. > > Since VSPD underruns may indeed cause [1] display flicker, we believe > that having a minimal/lightweight support for detecting and logging > such events would be extremely beneficial. Obviously, this only applies > to VSP2 modules having an interface to DU (i.e. not mem2mem). > > This implementation is heavily inspired by Koji Matsuoka's work [2-3], > but has been refactored to hopefully become production/mainline-friendly > (the original feature is intended for the development environment only). > > [1] https://lore.kernel.org/linux-renesas-soc/20220421161259.GA2660@lxhi-065 > [2] https://github.com/renesas-rcar/linux-bsp/commit/3469001c3098 > ("v4l: vsp1: Add underrun hung-up workaround") > [3] https://github.com/renesas-rcar/linux-bsp/commit/12ea79975a10 > ("v4l: vsp1: Add underrun debug messege option") Would you please provide brief high-level guidance/steering on this patch proposal, to define further direction? Many thanks in advance. Any criticism and/or simply the gut feeling would be very welcome. Best regards, Eugeniu