drm: vc4_dsi: Fix DMA channel and memory leak in vc4 (#3012)

Signed-off-by: Chris G Miller <chris@creative-electronics.net>

drivers/gpu/drm/vc4/vc4_dsi.c

@@ -1497,9 +1497,11 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 	/* DSI1 has a broken AXI slave that doesn't respond to writes
 	 * from the ARM.  It does handle writes from the DMA engine,
 	 * so set up a channel for talking to it.
+	 * Where possible managed resource providers are used, but the DMA channel
+	 * must - if acquired - be explicitly released prior to taking an error exit path.
 	 */
 	if (dsi->port == 1) {
-		dsi->reg_dma_mem = dma_alloc_coherent(dev, 4,
+		dsi->reg_dma_mem = dmam_alloc_coherent(dev, 4,
 						      &dsi->reg_dma_paddr,
 						      GFP_KERNEL);
 		if (!dsi->reg_dma_mem) {
@@ -1518,6 +1520,8 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 			return ret;
 		}
 
+		/* From here on, any error exits must release the dma channel */
+
 		/* Get the physical address of the device's registers.  The
 		 * struct resource for the regs gives us the bus address
 		 * instead.
@@ -1544,31 +1548,31 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 	if (ret) {
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "Failed to get interrupt: %d\n", ret);
-		return ret;
+		goto rel_dma_exit;
 	}
 
 	dsi->escape_clock = devm_clk_get(dev, "escape");
 	if (IS_ERR(dsi->escape_clock)) {
 		ret = PTR_ERR(dsi->escape_clock);
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "Failed to get escape clock: %d\n", ret);
-		return ret;
+		goto rel_dma_exit;
 	}
 
 	dsi->pll_phy_clock = devm_clk_get(dev, "phy");
 	if (IS_ERR(dsi->pll_phy_clock)) {
 		ret = PTR_ERR(dsi->pll_phy_clock);
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "Failed to get phy clock: %d\n", ret);
-		return ret;
+		goto rel_dma_exit;
 	}
 
 	dsi->pixel_clock = devm_clk_get(dev, "pixel");
 	if (IS_ERR(dsi->pixel_clock)) {
 		ret = PTR_ERR(dsi->pixel_clock);
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "Failed to get pixel clock: %d\n", ret);
-		return ret;
+		goto rel_dma_exit;
 	}
 
 	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
@@ -1583,26 +1587,28 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 		if (ret == -ENODEV)
 			return 0;
 
-		return ret;
+		goto rel_dma_exit;
 	}
 
 	if (panel) {
 		dsi->bridge = devm_drm_panel_bridge_add_typed(dev, panel,
 							      DRM_MODE_CONNECTOR_DSI);
-		if (IS_ERR(dsi->bridge))
-			return PTR_ERR(dsi->bridge);
+		if (IS_ERR(dsi->bridge)){
+			ret = PTR_ERR(dsi->bridge);
+			goto rel_dma_exit;
+		}
 	}
 
 	/* The esc clock rate is supposed to always be 100Mhz. */
 	ret = clk_set_rate(dsi->escape_clock, 100 * 1000000);
 	if (ret) {
 		dev_err(dev, "Failed to set esc clock: %d\n", ret);
-		return ret;
+		goto rel_dma_exit;
 	}
 
 	ret = vc4_dsi_init_phy_clocks(dsi);
 	if (ret)
-		return ret;
+		goto rel_dma_exit;
 
 	if (dsi->port == 1)
 		vc4->dsi1 = dsi;
@@ -1613,7 +1619,7 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 	ret = drm_bridge_attach(dsi->encoder, dsi->bridge, NULL, 0);
 	if (ret) {
 		dev_err(dev, "bridge attach failed: %d\n", ret);
-		return ret;
+		goto rel_dma_exit;
 	}
 	/* Disable the atomic helper calls into the bridge.  We
 	 * manually call the bridge pre_enable / enable / etc. calls
@@ -1630,6 +1636,11 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 	pm_runtime_enable(dev);
 
 	return 0;
+
+rel_dma_exit:
+	dma_release_channel(dsi->reg_dma_chan);
+
+	return ret;
 }
 
 static void vc4_dsi_unbind(struct device *dev, struct device *master,
@@ -1649,6 +1660,8 @@ static void vc4_dsi_unbind(struct device *dev, struct device *master,
 	list_splice_init(&dsi->bridge_chain, &dsi->encoder->bridge_chain);
 	drm_encoder_cleanup(dsi->encoder);
 
+	dma_release_channel(dsi->reg_dma_chan);
+
 	if (dsi->port == 1)
 		vc4->dsi1 = NULL;
 }