From patchwork Tue Jan 9 10:09:25 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Ripard X-Patchwork-Id: 10151539 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 40A7B60223 for ; Tue, 9 Jan 2018 10:10:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2578128A23 for ; Tue, 9 Jan 2018 10:10:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1A56328A1C; Tue, 9 Jan 2018 10:10:22 +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=-4.2 required=2.0 tests=BAYES_00, 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 BE84B28A26 for ; Tue, 9 Jan 2018 10:10:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 356CA6E6F8; Tue, 9 Jan 2018 10:09:53 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail.free-electrons.com (mail.free-electrons.com [62.4.15.54]) by gabe.freedesktop.org (Postfix) with ESMTP id 7220A6E6E9 for ; Tue, 9 Jan 2018 10:09:51 +0000 (UTC) Received: by mail.free-electrons.com (Postfix, from userid 110) id C4FB42072D; Tue, 9 Jan 2018 11:09:49 +0100 (CET) Received: from localhost (LStLambert-657-1-97-87.w90-63.abo.wanadoo.fr [90.63.216.87]) by mail.free-electrons.com (Postfix) with ESMTPSA id E8B68207B4; Tue, 9 Jan 2018 11:09:32 +0100 (CET) From: Maxime Ripard To: Daniel Vetter , David Airlie , Chen-Yu Tsai , Maxime Ripard Subject: [PATCH v3 12/13] drm/sun4i: backend: Make sure we don't have a commit pending Date: Tue, 9 Jan 2018 11:09:25 +0100 Message-Id: X-Mailer: git-send-email 2.14.3 In-Reply-To: References: In-Reply-To: References: Cc: Thomas Petazzoni , narmstrong@baylibre.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, thomas@vitsch.nl X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP If we try to read the backend registers while it fetches the new values, we end up with the value of some random register instead of the one we asked for. In order to prevent that, let's make sure that the very first thing we do during our atomic modesetting is to let the commit bit come to a rest. We don't have to worry about anything else since the only time we will trigger a new transaction is during the atomic_commit which comes much later. Reviewed-by: Chen-Yu Tsai Signed-off-by: Maxime Ripard --- drivers/gpu/drm/sun4i/sun4i_backend.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c index 4642f933765e..a18c86a15748 100644 --- a/drivers/gpu/drm/sun4i/sun4i_backend.c +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c @@ -297,6 +297,17 @@ static bool sun4i_backend_plane_uses_frontend(struct drm_plane_state *state) return sun4i_backend_plane_uses_scaler(state); } +static void sun4i_backend_atomic_begin(struct sunxi_engine *engine, + struct drm_crtc_state *old_state) +{ + u32 val; + + WARN_ON(regmap_read_poll_timeout(engine->regs, + SUN4I_BACKEND_REGBUFFCTL_REG, + val, !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL), + 100, 50000)); +} + static int sun4i_backend_atomic_check(struct sunxi_engine *engine, struct drm_crtc_state *crtc_state) { @@ -478,6 +489,7 @@ static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv, } static const struct sunxi_engine_ops sun4i_backend_engine_ops = { + .atomic_begin = sun4i_backend_atomic_begin, .atomic_check = sun4i_backend_atomic_check, .commit = sun4i_backend_commit, .layers_init = sun4i_layers_init,