soc/integration: Improve error handling for framebuffer without sdram

litex/soc/integration/soc.py

@@ -2367,10 +2367,14 @@ class LiteXSoC(SoC):
             size = 0x800000
             # If the intended region isn't contained in the main_ram region, adjust it to fit.
             main_ram_region = self.bus.regions.get("main_ram", None)
-            if main_ram_region is not None and not (
+            if main_ram_region is None:
+                self.logger.error("Video framebuffer requires SDRAM")
+                raise SoCError()
+            contained_in_main_ram = (
                 main_ram_region.origin < base
                 and base + size < main_ram_region.origin + main_ram_region.size
-            ):
+            )
+            if not contained_in_main_ram:
                 size = min(size, main_ram_region.size // 2)
                 base = main_ram_region.origin + main_ram_region.size - size
             self.bus.add_region(name, SoCRegion(
@@ -2381,6 +2385,9 @@ class LiteXSoC(SoC):
             base = self.bus.regions[name].origin
         hres = int(timings.split("@")[0].split("x")[0])
         vres = int(timings.split("@")[0].split("x")[1])
+        if not hasattr(self, "sdram"):
+            self.logger.error("Video framebuffer requires SDRAM")
+            raise SoCError()
         vfb = VideoFrameBuffer(self.sdram.crossbar.get_port(),
             hres   = hres,
             vres   = vres,