drm/simpledrm: Allow physical width and height configuration via panel node

Parse the width-mm and height-mm devicetree properties of the panel node,
and use this to set the DRM Display Mode instead of calculating it
based on a hardcoded DPI.

Signed-off-by: Rayyan Ansari <rayyan@ansari.sh>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230126182435.70544-2-rayyan@ansari.sh

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 63881a3754f8a0c5253388861de9e0592ecdfc58..c38d85848af8a4fccd8cd69cf739a8ab62d6a82c 100644 (file)
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -606,16 +606,12 @@ static const struct drm_mode_config_funcs simpledrm_mode_config_funcs = {
  */
 
 static struct drm_display_mode simpledrm_mode(unsigned int width,
-                                             unsigned int height)
+                                             unsigned int height,
+                                             unsigned int width_mm,
+                                             unsigned int height_mm)
 {
-       /*
-        * Assume a monitor resolution of 96 dpi to
-        * get a somewhat reasonable screen size.
-        */
        const struct drm_display_mode mode = {
-               DRM_MODE_INIT(60, width, height,
-                             DRM_MODE_RES_MM(width, 96ul),
-                             DRM_MODE_RES_MM(height, 96ul))
+               DRM_MODE_INIT(60, width, height, width_mm, height_mm)
        };
 
        return mode;
@@ -629,6 +625,8 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
        struct simpledrm_device *sdev;
        struct drm_device *dev;
        int width, height, stride;
+       int width_mm = 0, height_mm = 0;
+       struct device_node *panel_node;
        const struct drm_format_info *format;
        struct resource *res, *mem = NULL;
        struct drm_plane *primary_plane;
@@ -685,6 +683,12 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
                mem = simplefb_get_memory_of(dev, of_node);
                if (IS_ERR(mem))
                        return ERR_CAST(mem);
+               panel_node = of_parse_phandle(of_node, "panel", 0);
+               if (panel_node) {
+                       simplefb_read_u32_of(dev, panel_node, "width-mm", &width_mm);
+                       simplefb_read_u32_of(dev, panel_node, "height-mm", &height_mm);
+                       of_node_put(panel_node);
+               }
        } else {
                drm_err(dev, "no simplefb configuration found\n");
                return ERR_PTR(-ENODEV);
@@ -695,7 +699,16 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
                        return ERR_PTR(-EINVAL);
        }
 
-       sdev->mode = simpledrm_mode(width, height);
+       /*
+        * Assume a monitor resolution of 96 dpi if physical dimensions
+        * are not specified to get a somewhat reasonable screen size.
+        */
+       if (!width_mm)
+               width_mm = DRM_MODE_RES_MM(width, 96ul);
+       if (!height_mm)
+               height_mm = DRM_MODE_RES_MM(height, 96ul);
+
+       sdev->mode = simpledrm_mode(width, height, width_mm, height_mm);
        sdev->format = format;
        sdev->pitch = stride;