OMAPDSS: VENC: allow switching venc output type at runtime

VENC output type (composite/svideo) doesn't have to be fixed by board
wiring, it is possible to also provide composite signal through svideo
luminance connector (software enabled), which is what pandora does.

Having to recompile the kernel for users who have TV connector types
that don't match default board setting is very inconvenient, especially
for users of a consumer device, so add support for switching VENC output
type at runtime over a new sysfs file output_type.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Documentation/arm/OMAP/DSS

@@ -156,6 +156,7 @@ timings		Display timings (pixclock,xres/hfp/hbp/hsw,yres/vfp/vbp/vsw)
 		"pal" and "ntsc"
 panel_name
 tear_elim	Tearing elimination 0=off, 1=on
+output_type	Output type (video encoder only): "composite" or "svideo"
 
 There are also some debugfs files at <debugfs>/omapdss/ which show information
 about clocks and registers.

drivers/video/omap2/dss/venc.c

@@ -490,16 +490,68 @@ unsigned long venc_get_pixel_clock(void)
 	return 13500000;
 }
 
+static ssize_t display_output_type_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct omap_dss_device *dssdev = to_dss_device(dev);
+	const char *ret;
+
+	switch (dssdev->phy.venc.type) {
+	case OMAP_DSS_VENC_TYPE_COMPOSITE:
+		ret = "composite";
+		break;
+	case OMAP_DSS_VENC_TYPE_SVIDEO:
+		ret = "svideo";
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", ret);
+}
+
+static ssize_t display_output_type_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct omap_dss_device *dssdev = to_dss_device(dev);
+	enum omap_dss_venc_type new_type;
+
+	if (sysfs_streq("composite", buf))
+		new_type = OMAP_DSS_VENC_TYPE_COMPOSITE;
+	else if (sysfs_streq("svideo", buf))
+		new_type = OMAP_DSS_VENC_TYPE_SVIDEO;
+	else
+		return -EINVAL;
+
+	mutex_lock(&venc.venc_lock);
+
+	if (dssdev->phy.venc.type != new_type) {
+		dssdev->phy.venc.type = new_type;
+		if (dssdev->state == OMAP_DSS_DISPLAY_ACTIVE) {
+			venc_power_off(dssdev);
+			venc_power_on(dssdev);
+		}
+	}
+
+	mutex_unlock(&venc.venc_lock);
+
+	return size;
+}
+
+static DEVICE_ATTR(output_type, S_IRUGO | S_IWUSR,
+		display_output_type_show, display_output_type_store);
+
 /* driver */
 static int venc_panel_probe(struct omap_dss_device *dssdev)
 {
 	dssdev->panel.timings = omap_dss_pal_timings;
 
-	return 0;
+	return device_create_file(&dssdev->dev, &dev_attr_output_type);
 }
 
 static void venc_panel_remove(struct omap_dss_device *dssdev)
 {
+	device_remove_file(&dssdev->dev, &dev_attr_output_type);
 }
 
 static int venc_panel_enable(struct omap_dss_device *dssdev)