Re: [PATCH v9 2/6] video: add of helper for videomode

On Wed, Nov 14, 2012 at 01:00:45PM +0100, Thierry Reding wrote:

On Wed, Nov 14, 2012 at 12:43:19PM +0100, Steffen Trumtrar wrote:
[...]

quoted

+display-timings bindings
+============
+
+display timings node

I didn't express myself very clearly here =). The way I think this
should be written is "display-timings node".

quoted

+required properties:
+ - hactive, vactive: Display resolution
+ - hfront-porch, hback-porch, hsync-len: Horizontal Display timing parameters
+   in pixels
+   vfront-porch, vback-porch, vsync-len: Vertical display timing parameters in
+   lines
+ - clock-frequency: displayclock in Hz

I still think "displayclock" should be two words: "display clock".

quoted

+/**
+ * of_get_display_timings - parse all display_timing entries from a device_node
+ * @np: device_node with the subnodes
+ **/
+struct display_timings *of_get_display_timings(struct device_node *np)
+{

[...]

quoted

+	disp->num_timings = 0;
+	disp->native_mode = 0;
+
+	for_each_child_of_node(timings_np, entry) {
+		struct display_timing *dt;
+
+		dt = of_get_display_timing(entry);
+		if (!dt) {
+			/* to not encourage wrong devicetrees, fail in case of an error */
+			pr_err("%s: error in timing %d\n", __func__, disp->num_timings+1);
+			goto timingfail;

I believe you're still potentially leaking memory here. In case you have
5 entries for instance, and the last one fails to parse, then this will
cause the memory allocated for the 4 correct entries to be lost.

Can't you just call display_timings_release() in this case and then jump
to dispfail? That would still leak the native_mode device node. Maybe it
would be better to keep timingfail but modify it to free the display
timings with display_timings_release() instead? See below.

quoted

+		}
+
+		if (native_mode = entry)
+			disp->native_mode = disp->num_timings;
+
+		disp->timings[disp->num_timings] = dt;
+		disp->num_timings++;
+	}
+	of_node_put(timings_np);
+	of_node_put(native_mode);
+
+	if (disp->num_timings > 0)
+		pr_info("%s: got %d timings. Using timing #%d as default\n", __func__,
+			disp->num_timings , disp->native_mode + 1);
+	else {
+		pr_err("%s: no valid timings specified\n", __func__);
+		display_timings_release(disp);
+		return NULL;
+	}
+	return disp;
+
+timingfail:
+	if (native_mode)
+		of_node_put(native_mode);
+	kfree(disp->timings);

Call display_timings_release(disp) instead of kfree(disp->timings)?

Yes. That would be the appropriate way to fail here. Done.

quoted

diff --git a/include/linux/of_videomode.h b/include/linux/of_videomode.h
new file mode 100644
index 0000000..4138758
--- /dev/null
+++ b/include/linux/of_videomode.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
+ *
+ * videomode of-helpers
+ *
+ * This file is released under the GPLv2
+ */
+
+#ifndef __LINUX_OF_VIDEOMODE_H
+#define __LINUX_OF_VIDEOMODE_H
+
+#include <linux/videomode.h>
+#include <linux/of.h>
+
+int of_get_videomode(struct device_node *np, struct videomode *vm, int index);
+#endif /* __LINUX_OF_VIDEOMODE_H */

Nit: should have a blank line before #endif.

Thierry

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