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From: Douglas Anderson <dianders@chromium.org>
To: Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Sam Ravnborg <sam@ravnborg.org>, Wolfram Sang <wsa@kernel.org>
Cc: Stephen Boyd <swboyd@chromium.org>,
	robdclark@chromium.org,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>,
	Steev Klimaszewski <steev@kali.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	linux-arm-msm@vger.kernel.org, Linus W <linus.walleij@linaro.org>,
	Douglas Anderson <dianders@chromium.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Thierry Reding <thierry.reding@gmail.com>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 27/27] drm/panel: panel-simple: Prepare/unprepare are refcounted, not forced
Date: Fri, 16 Apr 2021 15:39:50 -0700
Message-ID: <20210416153909.v4.27.I502f2a92ddd36c3d28d014dd75e170c2d405a0a5@changeid> (raw)
In-Reply-To: <20210416223950.3586967-1-dianders@chromium.org>

Historically simple-panel had code to make sure that if prepare() was
called on an already-prepared panel that it was a no-op. Similarly if
unprepare() was called on an already-unprepared panel it was also a
no-op. Essentially it means that these functions always "forced" the
value to be whatever the caller wanted it to be. You can see that the
forcing behavior dates back at least as far as 2014 by looking at
commit 613a633e7a56 ("drm/panel: simple: Add proper definition for
prepare and unprepare").

Apparently the code supporting the historical behavior may not be
needed [1] and prepare() / unprepare() are supposed to be
balanced. Let's try removing it and see if anyone breaks! If they do
then we can have a debate about whether we should change that code or
revert this patch. :-) If nobody breaks then we've nicely saved a few
lines of code and some complexity.

[1] https://lore.kernel.org/r/YHePsQgqOau1V5lD@pendragon.ideasonboard.com

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

(no changes since v1)

 drivers/gpu/drm/panel/panel-simple.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 5a2953c4ca44..a2c3008af7e5 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -176,8 +176,6 @@ struct panel_simple {
 	bool enabled;
 	bool no_hpd;
 
-	bool prepared;
-
 	ktime_t prepared_time;
 	ktime_t unprepared_time;
 
@@ -355,18 +353,12 @@ static int panel_simple_suspend(struct device *dev)
 
 static int panel_simple_unprepare(struct drm_panel *panel)
 {
-	struct panel_simple *p = to_panel_simple(panel);
 	int ret;
 
-	/* Unpreparing when already unprepared is a no-op */
-	if (!p->prepared)
-		return 0;
-
 	pm_runtime_mark_last_busy(panel->dev);
 	ret = pm_runtime_put_autosuspend(panel->dev);
 	if (ret < 0)
 		return ret;
-	p->prepared = false;
 
 	return 0;
 }
@@ -475,18 +467,12 @@ static int panel_simple_prepare(struct drm_panel *panel)
 	struct panel_simple *p = to_panel_simple(panel);
 	int ret;
 
-	/* Preparing when already prepared is a no-op */
-	if (p->prepared)
-		return 0;
-
 	ret = pm_runtime_get_sync(panel->dev);
 	if (ret < 0) {
 		pm_runtime_put_autosuspend(panel->dev);
 		return ret;
 	}
 
-	p->prepared = true;
-
 	return 0;
 }
 
-- 
2.31.1.368.gbe11c130af-goog


  parent reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16 22:39 [PATCH v4 00/27] drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 01/27] drm/bridge: Fix the stop condition of drm_bridge_chain_pre_enable() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 02/27] drm/bridge: ti-sn65dsi86: Simplify refclk handling Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 03/27] drm/bridge: ti-sn65dsi86: Remove incorrectly tagged kerneldoc comment Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 04/27] drm/bridge: ti-sn65dsi86: Reorder remove() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 05/27] drm/bridge: ti-sn65dsi86: Move drm_panel_unprepare() to post_disable() Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 06/27] drm/bridge: ti-sn65dsi86: Get rid of the useless detect() function Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 07/27] drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare Douglas Anderson
2021-04-16 22:39 ` [PATCH v4 08/27] drm/bridge: ti-sn65dsi86: Rename the main driver data structure Douglas Anderson
2021-04-23 14:28   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 09/27] drm/bridge: ti-sn65dsi86: More renames in prep for sub-devices Douglas Anderson
2021-04-23 14:30   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 10/27] drm/bridge: ti-sn65dsi86: Clean debugfs code Douglas Anderson
2021-04-23 14:35   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 11/27] drm/bridge: ti-sn65dsi86: Add local var for "dev" to simplify probe Douglas Anderson
2021-04-23 14:38   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 12/27] drm/bridge: ti-sn65dsi86: Cleanup managing of drvdata Douglas Anderson
2021-04-23 14:38   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 13/27] drm/bridge: ti-sn65dsi86: Use devm to do our runtime_disable Douglas Anderson
2021-04-23 14:39   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 14/27] drm/bridge: ti-sn65dsi86: Move all the chip-related init to the start Douglas Anderson
2021-04-23 14:41   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 15/27] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers Douglas Anderson
2021-04-23 14:49   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 16/27] drm/panel: panel-simple: Get rid of hacky HPD chicken-and-egg code Douglas Anderson
2021-04-23 14:50   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 17/27] drm/bridge: ti-sn65dsi86: Use pm_runtime autosuspend Douglas Anderson
2021-04-23 14:51   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 18/27] drm/bridge: ti-sn65dsi86: Code motion of refclk management functions Douglas Anderson
2021-04-23 14:51   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 19/27] drm/bridge: ti-sn65dsi86: If refclk, DP AUX can happen w/out pre-enable Douglas Anderson
2021-04-23 14:56   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 20/27] drm/bridge: ti-sn65dsi86: Promote the AUX channel to its own sub-dev Douglas Anderson
2021-04-23 14:59   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 21/27] i2c: i2c-core-of: Fix corner case of finding adapter by node Douglas Anderson
2021-04-23 15:12   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 22/27] drm/panel: panel-simple: Remove extra call: drm_connector_update_edid_property() Douglas Anderson
2021-04-23 15:15   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 23/27] drm/panel: panel-simple: Power the panel when reading the EDID Douglas Anderson
2021-04-23 15:16   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 24/27] drm/panel: panel-simple: Cache the EDID as long as we retain power Douglas Anderson
2021-04-23 16:12   ` Bjorn Andersson
2021-04-23 16:30     ` Doug Anderson
2021-04-16 22:39 ` [PATCH v4 25/27] drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC Douglas Anderson
2021-04-23 16:13   ` Bjorn Andersson
2021-04-16 22:39 ` [PATCH v4 26/27] arm64: dts: qcom: Link the panel to the bridge's DDC bus Douglas Anderson
2021-04-23 16:16   ` Bjorn Andersson
2021-04-16 22:39 ` Douglas Anderson [this message]
2021-04-23 16:16   ` [PATCH v4 27/27] drm/panel: panel-simple: Prepare/unprepare are refcounted, not forced Bjorn Andersson
2021-04-23 16:46   ` Doug Anderson
2021-04-20 16:42 ` [PATCH v4 00/27] drm: Fix EDID reading on ti-sn65dsi86; solve some chicken-and-egg problems Doug Anderson

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