Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752645AbdGMOlo (ORCPT ); Thu, 13 Jul 2017 10:41:44 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:60783 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752179AbdGMOlW (ORCPT ); Thu, 13 Jul 2017 10:41:22 -0400 From: Maxime Ripard To: Daniel Vetter , David Airlie , Jani Nikula , Sean Paul , Inki Dae , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Kukjin Kim , Krzysztof Kozlowski , Laurent Pinchart , Mark Yao , Heiko Stuebner , Chen-Yu Tsai , Maxime Ripard Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-rockchip@lists.infradead.org Subject: [PATCH 4/4] drm/sun4i: make sure we don't have a commit pending Date: Thu, 13 Jul 2017 16:41:16 +0200 Message-Id: X-Mailer: git-send-email 2.13.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2161 Lines: 59 In the earlier display engine designs, any register access while a commit is pending is forbidden. One of the symptoms is that reading a register will return another, random, register value which can lead to register corruptions if we ever do a read/modify/write cycle. Signed-off-by: Maxime Ripard --- drivers/gpu/drm/sun4i/sun4i_backend.c | 14 ++++++++++++++ drivers/gpu/drm/sun4i/sun4i_crtc.c | 1 + 2 files changed, 15 insertions(+) diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c index cf480218daa5..ce1f40f7511e 100644 --- a/drivers/gpu/drm/sun4i/sun4i_backend.c +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c @@ -67,6 +67,19 @@ static void sun4i_backend_commit(struct sunxi_engine *engine) SUN4I_BACKEND_REGBUFFCTL_LOADCTL); } +static int sun4i_backend_commit_poll(struct sunxi_engine *engine) +{ + u32 val; + + DRM_DEBUG_DRIVER("Polling for the commit to end\n"); + + return regmap_read_poll_timeout(engine->regs, + SUN4I_BACKEND_REGBUFFCTL_REG, + val, + !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL), + 100, 50000); +} + void sun4i_backend_layer_enable(struct sun4i_backend *backend, int layer, bool enable) { @@ -330,6 +343,7 @@ static int sun4i_backend_of_get_id(struct device_node *node) static const struct sunxi_engine_ops sun4i_backend_engine_ops = { .commit = sun4i_backend_commit, + .commit_poll = sun4i_backend_commit_poll, .layers_init = sun4i_layers_init, .apply_color_correction = sun4i_backend_apply_color_correction, .disable_color_correction = sun4i_backend_disable_color_correction, diff --git a/drivers/gpu/drm/sun4i/sun4i_crtc.c b/drivers/gpu/drm/sun4i/sun4i_crtc.c index 2eba1d8639d8..31550493fa1d 100644 --- a/drivers/gpu/drm/sun4i/sun4i_crtc.c +++ b/drivers/gpu/drm/sun4i/sun4i_crtc.c @@ -34,6 +34,7 @@ static void sun4i_crtc_atomic_begin(struct drm_crtc *crtc, struct drm_crtc_state *old_state) { struct sun4i_crtc *scrtc = drm_crtc_to_sun4i_crtc(crtc); + struct sunxi_engine *engine = scrtc->engine; struct drm_device *dev = crtc->dev; unsigned long flags; -- git-series 0.9.1