[PATCH v6 3/5] drm/modes: Add of_get_drm_panel_display_mode()

[Noralf Trønnes]

Add a function to get a drm_display_mode from a panel-timing
device tree subnode.

Suggested-by: Sam Ravnborg <s...@ravnborg.org>
Reviewed-by: Sam Ravnborg <s...@ravnborg.org>
Signed-off-by: Noralf Trønnes <nor...@tronnes.org>
---
 drivers/gpu/drm/drm_modes.c | 49 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_modes.h     |  8 ++++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 77a4c8dd0bb8..3f819c7a021b 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -35,6 +35,7 @@
 #include <linux/list_sort.h>
 #include <linux/export.h>
 
+#include <video/of_display_timing.h>
 #include <video/of_videomode.h>
 #include <video/videomode.h>
 
@@ -727,6 +728,54 @@ int of_get_drm_display_mode(struct device_node *np,
        return 0;
 }
 EXPORT_SYMBOL_GPL(of_get_drm_display_mode);
+
+/**
+ * of_get_drm_panel_display_mode - get a panel-timing drm_display_mode from 
devicetree
+ * @np: device_node with the panel-timing specification
+ * @dmode: will be set to the return value
+ * @bus_flags: information about pixelclk, sync and DE polarity
+ *
+ * The Device Tree properties width-mm and height-mm will be read and set on
+ * the display mode if they are present.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int of_get_drm_panel_display_mode(struct device_node *np,
+                                 struct drm_display_mode *dmode, u32 
*bus_flags)
+{
+       u32 width_mm = 0, height_mm = 0;
+       struct display_timing timing;
+       struct videomode vm;
+       int ret;
+
+       ret = of_get_display_timing(np, "panel-timing", &timing);
+       if (ret)
+               return ret;
+
+       videomode_from_timing(&timing, &vm);
+
+       memset(dmode, 0, sizeof(*dmode));
+       drm_display_mode_from_videomode(&vm, dmode);
+       if (bus_flags)
+               drm_bus_flags_from_videomode(&vm, bus_flags);
+
+       ret = of_property_read_u32(np, "width-mm", &width_mm);
+       if (ret && ret != -EINVAL)
+               return ret;
+
+       ret = of_property_read_u32(np, "height-mm", &height_mm);
+       if (ret && ret != -EINVAL)
+               return ret;
+
+       dmode->width_mm = width_mm;
+       dmode->height_mm = height_mm;
+
+       drm_mode_debug_printmodeline(dmode);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(of_get_drm_panel_display_mode);
 #endif /* CONFIG_OF */
 #endif /* CONFIG_VIDEOMODE_HELPERS */
 
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index 29ba4adf0c53..2fa6b2c33b3f 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -466,6 +466,8 @@ void drm_bus_flags_from_videomode(const struct videomode 
*vm, u32 *bus_flags);
 int of_get_drm_display_mode(struct device_node *np,
                            struct drm_display_mode *dmode, u32 *bus_flags,
                            int index);
+int of_get_drm_panel_display_mode(struct device_node *np,
+                                 struct drm_display_mode *dmode, u32 
*bus_flags);
 #else
 static inline int of_get_drm_display_mode(struct device_node *np,
                                          struct drm_display_mode *dmode,
@@ -473,6 +475,12 @@ static inline int of_get_drm_display_mode(struct 
device_node *np,
 {
        return -EINVAL;
 }
+
+static inline int of_get_drm_panel_display_mode(struct device_node *np,
+                                               struct drm_display_mode *dmode, 
u32 *bus_flags)
+{
+       return -EINVAL;
+}
 #endif
 
 void drm_mode_set_name(struct drm_display_mode *mode);
-- 
2.33.0