linux-kernel - [PATCH] drm/bridge: Add missing pm_runtime_put

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Date:   Wed, 19 Jan 2022 07:36:00 -0800
From:   Yongzhi Liu <lyz_cs@....edu.cn>
To:     a.hajda@...sung.com, narmstrong@...libre.com,
        robert.foss@...aro.org, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...il.com, airlied@...ux.ie,
        daniel@...ll.ch
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yongzhi Liu <lyz_cs@....edu.cn>
Subject: [PATCH] drm/bridge: Add missing pm_runtime_put_sync

pm_runtime_get_sync() will increase the rumtime PM counter
even it returns an error. Thus a pairing decrement is needed
to prevent refcount leak. Fix this by replacing this API with
pm_runtime_resume_and_get(), which will not change the runtime
PM counter on error. Besides, a matching decrement is needed
on the error handling path to keep the counter balanced.

Signed-off-by: Yongzhi Liu <lyz_cs@....edu.cn>
---
 drivers/gpu/drm/bridge/nwl-dsi.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index 9282e61..e7dce5a 100644
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -862,18 +862,19 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
 	memcpy(&dsi->mode, adjusted_mode, sizeof(dsi->mode));
 	drm_mode_debug_printmodeline(adjusted_mode);
 
-	pm_runtime_get_sync(dev);
+	if (pm_runtime_resume_and_get(dev) < 0)
+		return;
 
 	if (clk_prepare_enable(dsi->lcdif_clk) < 0)
-		return;
+		goto runtime_put;
 	if (clk_prepare_enable(dsi->core_clk) < 0)
-		return;
+		goto runtime_put;
 
 	/* Step 1 from DSI reset-out instructions */
 	ret = reset_control_deassert(dsi->rst_pclk);
 	if (ret < 0) {
 		DRM_DEV_ERROR(dev, "Failed to deassert PCLK: %d\n", ret);
-		return;
+		goto runtime_put;
 	}
 
 	/* Step 2 from DSI reset-out instructions */
@@ -883,13 +884,17 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
 	ret = reset_control_deassert(dsi->rst_esc);
 	if (ret < 0) {
 		DRM_DEV_ERROR(dev, "Failed to deassert ESC: %d\n", ret);
-		return;
+		goto runtime_put;
 	}
 	ret = reset_control_deassert(dsi->rst_byte);
 	if (ret < 0) {
 		DRM_DEV_ERROR(dev, "Failed to deassert BYTE: %d\n", ret);
-		return;
+		goto runtime_put;
 	}
+
+runtime_put:
+	pm_runtime_put_sync(dev);
+	return;
 }
 
 static void
-- 
2.7.4