From patchwork Fri Feb 8 09:53:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Ripard X-Patchwork-Id: 10802577 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 802961390 for ; Fri, 8 Feb 2019 09:53:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 70CF72DD62 for ; Fri, 8 Feb 2019 09:53:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6552D2DD65; Fri, 8 Feb 2019 09:53:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 26B6C2DD62 for ; Fri, 8 Feb 2019 09:53:42 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4D4996ED78; Fri, 8 Feb 2019 09:53:41 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from relay12.mail.gandi.net (relay12.mail.gandi.net [217.70.178.232]) by gabe.freedesktop.org (Postfix) with ESMTPS id E6A256ED78 for ; Fri, 8 Feb 2019 09:53:39 +0000 (UTC) Received: from localhost (aaubervilliers-681-1-80-177.w90-88.abo.wanadoo.fr [90.88.22.177]) (Authenticated sender: maxime.ripard@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id C4530200007; Fri, 8 Feb 2019 09:53:35 +0000 (UTC) From: Maxime Ripard To: Maarten Lankhorst , Sean Paul , Maxime Ripard Subject: [PATCH v2 3/9] drm/sun4i: dsi: Change the start delay calculation Date: Fri, 8 Feb 2019 10:53:16 +0100 Message-Id: <6e5f72e68f47ca0223877464bf12f0c3f3978de8.1549619502.git-series.maxime.ripard@bootlin.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: References: MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bbrezillon@kernel.org, dri-devel@lists.freedesktop.org, Paul Kocialkowski , Chen-Yu Tsai , Thomas Petazzoni , Jagan Teki , linux-arm-kernel@lists.infradead.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP The current calculation for the video start delay in the current DSI driver is that it is the total vertical size, minus the front porch and sync length, plus 1. This equals to the active vertical size plus the back porch plus 1. That 1 is coming in the Allwinner BSP from an variable that is set to 1. However, if we look at the Allwinner BSP more closely, and especially in the "legacy" code for the display (in drivers/video/sunxi/legacy/), we can see that this variable is actually computed from the porches and the sync minus 10, clamped between 8 and 100. This fixes the start delay symptom we've seen on some panels (vblank timeouts with vertical white stripes at the bottom of the panel). Signed-off-by: Maxime Ripard --- drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c index 380fc527a707..9471fa695ec7 100644 --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c @@ -357,7 +357,9 @@ static void sun6i_dsi_inst_init(struct sun6i_dsi *dsi, static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi, struct drm_display_mode *mode) { - return mode->vtotal - (mode->vsync_end - mode->vdisplay) + 1; + u16 start = clamp(mode->vtotal - mode->vdisplay - 10, 8, 100); + + return mode->vtotal - (mode->vsync_end - mode->vdisplay) + start; } static void sun6i_dsi_setup_burst(struct sun6i_dsi *dsi,