linux-kernel - [PATCH] drm/omap: Fix runtime PM imbalance in dsi_runtime

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Message-Id: <20200821074506.32359-1-dinghao.liu@zju.edu.cn>
Date:   Fri, 21 Aug 2020 15:45:03 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn, kjlu@....edu
Cc:     Tomi Valkeinen <tomi.valkeinen@...com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        Tony Lindgren <tony@...mide.com>,
        zhengbin <zhengbin13@...wei.com>, Kevin Hilman <khilman@...com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/omap: Fix runtime PM imbalance in dsi_runtime_get

pm_runtime_get_sync() increments the runtime PM usage counter
even when it returns an error code. However, users of
dsi_runtime_get(), a direct wrapper of pm_runtime_get_sync(),
assume that PM usage counter will not change on error. Thus a
pairing decrement is needed on the error handling path to keep
the counter balanced.

Fixes: 4fbafaf371be7 ("OMAP: DSS2: Use PM runtime & HWMOD support")
Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---
 drivers/gpu/drm/omapdrm/dss/dsi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
index eeccf40bae41..973bfa14a104 100644
--- a/drivers/gpu/drm/omapdrm/dss/dsi.c
+++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
@@ -1112,8 +1112,11 @@ static int dsi_runtime_get(struct dsi_data *dsi)
 	DSSDBG("dsi_runtime_get\n");
 
 	r = pm_runtime_get_sync(dsi->dev);
-	WARN_ON(r < 0);
-	return r < 0 ? r : 0;
+	if (WARN_ON(r < 0)) {
+		pm_runtime_put_noidle(dsi->dev);
+		return r;
+	}
+	return 0;
 }
 
 static void dsi_runtime_put(struct dsi_data *dsi)
-- 
2.17.1