drm/omap: dss: Add support for reporting memory bandwidth limitation

The get_memory_bandwidth_limit() in dispc_ops can be used to query the
memory bandwidth limit of dispc by upper layers.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/omapdrm/dss/dispc.c

@@ -4325,6 +4325,17 @@ static void dispc_free_irq(void *dev_id)
 	dispc.user_data = NULL;
 }
 
+static u32 dispc_get_memory_bandwidth_limit(void)
+{
+	u32 limit = 0;
+
+	/* Optional maximum memory bandwidth */
+	of_property_read_u32(dispc.pdev->dev.of_node, "max-memory-bandwidth",
+			     &limit);
+
+	return limit;
+}
+
 /*
  * Workaround for errata i734 in DSS dispc
  *  - LCD1 Gamma Correction Is Not Working When GFX Pipe Is Disabled
@@ -4497,6 +4508,8 @@ static const struct dispc_ops dispc_ops = {
 	.get_num_ovls = dispc_get_num_ovls,
 	.get_num_mgrs = dispc_get_num_mgrs,
 
+	.get_memory_bandwidth_limit = dispc_get_memory_bandwidth_limit,
+
 	.mgr_enable = dispc_mgr_enable,
 	.mgr_is_enabled = dispc_mgr_is_enabled,
 	.mgr_get_vsync_irq = dispc_mgr_get_vsync_irq,

drivers/gpu/drm/omapdrm/dss/omapdss.h

@@ -695,6 +695,8 @@ struct dispc_ops {
 	int (*get_num_ovls)(void);
 	int (*get_num_mgrs)(void);
 
+	u32 (*get_memory_bandwidth_limit)(void);
+
 	void (*mgr_enable)(enum omap_channel channel, bool enable);
 	bool (*mgr_is_enabled)(enum omap_channel channel);
 	u32 (*mgr_get_vsync_irq)(enum omap_channel channel);