panel: Add basic support for parsing DTBs from newer SoCs

Newer SoCs use a qcom,mdss-dsi-display-timings subnode, which allows
defining multiple possible display modes (resolution, refresh rate, ...)
for one panel. The generator does not attemt to support this fully (yet!),
for now we just adjust the parsing a bit and pick the first timing.

Author: stephan-gh

fdt2.py

@@ -21,6 +21,12 @@ def subnodes(self, parent):
 			yield offset
 			offset = self.next_subnode(offset, [FDT_ERR_NOTFOUND])
 
+	def subnode_or_none(self, parentoffset, name):
+		offset = self.subnode_offset(parentoffset, name, [FDT_ERR_NOTFOUND])
+		if offset == -FDT_ERR_NOTFOUND:
+			return None
+		return offset
+
 	def getprop_or_none(self, nodeoffset, prop_name):
 		prop = self.getprop(nodeoffset, prop_name, [FDT_ERR_NOTFOUND])
 		if prop == -FDT_ERR_NOTFOUND:

panel.py

@@ -107,13 +107,13 @@ def __init__(self, prefix: str, size: str) -> None:
 			self.prefix = prefix
 			self.size = size
 
-	def __init__(self, fdt: Fdt2, node: int, t: Type) -> None:
+	def __init__(self, fdt: Fdt2, panel_node: int, mode_node: int, t: Type) -> None:
 		self.type = type
-		self.px = fdt.getprop(node, f'qcom,mdss-dsi-panel-{t.size}').as_int32()
-		self.fp = fdt.getprop(node, f'qcom,mdss-dsi-{t.prefix}-front-porch').as_int32()
-		self.bp = fdt.getprop(node, f'qcom,mdss-dsi-{t.prefix}-back-porch').as_int32()
-		self.pw = fdt.getprop(node, f'qcom,mdss-dsi-{t.prefix}-pulse-width').as_int32()
-		self.size = fdt.getprop_int32(node, f'qcom,mdss-pan-physical-{t.size}-dimension')
+		self.px = fdt.getprop(mode_node, f'qcom,mdss-dsi-panel-{t.size}').as_int32()
+		self.fp = fdt.getprop(mode_node, f'qcom,mdss-dsi-{t.prefix}-front-porch').as_int32()
+		self.bp = fdt.getprop(mode_node, f'qcom,mdss-dsi-{t.prefix}-back-porch').as_int32()
+		self.pw = fdt.getprop(mode_node, f'qcom,mdss-dsi-{t.prefix}-pulse-width').as_int32()
+		self.size = fdt.getprop_int32(panel_node, f'qcom,mdss-pan-physical-{t.size}-dimension')
 
 
 @dataclass
@@ -184,6 +184,22 @@ def _remove_before(text: str, sub: str) -> str:
 	return text[i + 1:] if i >= 0 else text
 
 
+def _find_mode_node(fdt: Fdt2, node: int) -> int:
+	timings_node = fdt.subnode_or_none(node, "qcom,mdss-dsi-display-timings")
+	if timings_node is None:
+		return node
+
+	mode_node = None
+	for timing in fdt.subnodes(timings_node):
+		if mode_node:
+			print("WARNING: Multiple display timings are not supported yet, using first!")
+			break
+		mode_node = timing
+
+	assert mode_node, "No display timings found"
+	return mode_node
+
+
 class Panel:
 	def __init__(self, name: str, fdt: Fdt2, node: int) -> None:
 		self.name = name
@@ -192,9 +208,14 @@ def __init__(self, name: str, fdt: Fdt2, node: int) -> None:
 		self.short_id = _replace_all(self.id, '_panel', '_video', '_vid', '_cmd',
 									 '_hd', '_qhd', '_720p', '_1080p',
 									 '_wvga', '_fwvga', '_qvga', '_xga', '_wxga')
-		self.h = Dimension(fdt, node, Dimension.Type.HORIZONTAL)
-		self.v = Dimension(fdt, node, Dimension.Type.VERTICAL)
-		self.framerate = fdt.getprop(node, 'qcom,mdss-dsi-panel-framerate').as_int32()
+
+		# Newer SoCs can use panels in different modes (resolution, refresh rate etc).
+		# We don't support this properly yet but many panels just have a single mode
+		# ("timing") defined, so let's try to support this here.
+		mode_node = _find_mode_node(fdt, node)
+		self.h = Dimension(fdt, node, mode_node, Dimension.Type.HORIZONTAL)
+		self.v = Dimension(fdt, node, mode_node, Dimension.Type.VERTICAL)
+		self.framerate = fdt.getprop(mode_node, 'qcom,mdss-dsi-panel-framerate').as_int32()
 		self.bpp = fdt.getprop(node, 'qcom,mdss-dsi-bpp').as_int32()
 		self.mode = Mode(fdt.getprop(node, 'qcom,mdss-dsi-panel-type').as_str())
 		self.traffic_mode = TrafficMode.parse(fdt.getprop(node, 'qcom,mdss-dsi-traffic-mode'))
@@ -227,8 +248,8 @@ def __init__(self, name: str, fdt: Fdt2, node: int) -> None:
 			self.reset_seq = None
 
 		self.cmds = {
-			'on': CommandSequence(fdt, node, 'on'),
-			'off': CommandSequence(fdt, node, 'off')
+			'on': CommandSequence(fdt, mode_node, 'on'),
+			'off': CommandSequence(fdt, mode_node, 'off')
 		}
 
 		# If all commands are sent in LPM, add flag globally
@@ -259,3 +280,13 @@ def find(fdt: Fdt2) -> Iterator[Panel]:
 				panel = Panel.parse(fdt, sub)
 				if panel:
 					yield panel
+
+		# Newer device trees do not necessarily have panels below MDP,
+		# search for qcom,dsi-display node instead
+		for display in fdt.find_by_compatible('qcom,dsi-display'):
+			# Actual display node is pointed to by qcom,dsi-panel
+			phandle = fdt.getprop(display, 'qcom,dsi-panel').as_uint32()
+			offset = fdt.node_offset_by_phandle(phandle)
+			panel = Panel.parse(fdt, offset)
+			if panel:
+				yield panel