drm/msm: a5xx: fix possible object reference leak

The call to of_get_child_by_name returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

Detected by coccinelle with the following warnings:
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:57:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 47, but without a corresponding object release within this function.
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:66:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 47, but without a corresponding object release within this function.
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:118:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 47, but without a corresponding object release within this function.
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:57:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 51, but without a corresponding object release within this function.
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:66:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 51, but without a corresponding object release within this function.
drivers/gpu/drm/msm/adreno/a5xx_gpu.c:118:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 51, but without a corresponding object release within this function.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jordan Crouse <jcrouse@codeaurora.org>
Cc: Mamta Shukla <mamtashukla555@gmail.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Sharat Masetty <smasetty@codeaurora.org>
Cc: linux-arm-msm@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: freedreno@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org (open list)
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a5xx_gpu.c

@@ -34,7 +34,7 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname)
 {
 	struct device *dev = &gpu->pdev->dev;
 	const struct firmware *fw;
-	struct device_node *np;
+	struct device_node *np, *mem_np;
 	struct resource r;
 	phys_addr_t mem_phys;
 	ssize_t mem_size;
@@ -48,11 +48,13 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname)
 	if (!np)
 		return -ENODEV;
 
-	np = of_parse_phandle(np, "memory-region", 0);
-	if (!np)
+	mem_np = of_parse_phandle(np, "memory-region", 0);
+	of_node_put(np);
+	if (!mem_np)
 		return -EINVAL;
 
-	ret = of_address_to_resource(np, 0, &r);
+	ret = of_address_to_resource(mem_np, 0, &r);
+	of_node_put(mem_np);
 	if (ret)
 		return ret;