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Message-ID: <20231013085424.7137-1-a-bhatia1@ti.com>
Date: Fri, 13 Oct 2023 14:24:24 +0530
From: Aradhya Bhatia <a-bhatia1@...com>
To: Rob Herring <robh+dt@...nel.org>,
Frank Rowand <frowand.list@...il.com>
CC: Devicetree List <devicetree@...r.kernel.org>,
Linux Kernel List <linux-kernel@...r.kernel.org>,
Andrew Davis <afd@...com>, Nishanth Menon <nm@...com>,
Vignesh Raghavendra <vigneshr@...com>,
Devarsh Thakkar <devarsht@...com>,
Jai Luthra <j-luthra@...com>,
Jayesh Choudhary <j-choudhary@...com>,
Aradhya Bhatia <a-bhatia1@...com>
Subject: [PATCH] scripts/dtc: Allow ports to have a single port@0 child
Exempt 'ports' from the rule which asserts that nodes with single child
node having reg = 0, should not have the '#size-cells' and
'#address-cells' properties.
Ports of certain hardware do need to be described as only having a
single child node 'port@0', especially when hardware has multiple ports,
and the other ports 'port@x' are planned to be added subsequently. In
such cases, just using 'port', would be an inaccurate hardware
description.
For example, Texas Instruments' DSS (display-subsystem), which has 2 or
4 video ports depending on the SoC. Describing the first video port with
just 'port' under ports would be inaccurate and even slightly
misleading. Simply using port@0 (when other ports are not added)
produces the following warning, while making dtbs with W=1 flag set[0].
code-block ::
Warning (graph_child_address): /bus@...000/dss@...0000/ports:
graph node has single child node 'port@0',
#address-cells/#size-cells are not necessary
Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
[0]: https://lore.kernel.org/all/570903b6-8239-d44a-5fac-71700804cb5d@ti.com/
---
scripts/dtc/checks.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/scripts/dtc/checks.c b/scripts/dtc/checks.c
index 9f31d2607182..705aa0fbcfa2 100644
--- a/scripts/dtc/checks.c
+++ b/scripts/dtc/checks.c
@@ -1797,9 +1797,18 @@ static void check_graph_child_address(struct check *c, struct dt_info *dti,
cnt++;
}
- if (cnt == 1 && node->addr_cells != -1)
+ if (cnt == 1 && node->addr_cells != -1) {
+ /*
+ * The graph node "ports" are exempt from this rule, because
+ * certain hardware do need to be described as only having a
+ * signle port with reg = 0.
+ */
+ if (!strcmp(node->name, "ports"))
+ return;
+
FAIL(c, dti, node, "graph node has single child node '%s', #address-cells/#size-cells are not necessary",
node->children->name);
+ }
}
WARNING(graph_child_address, check_graph_child_address, NULL, &graph_nodes);
base-commit: e3b18f7200f45d66f7141136c25554ac1e82009b
--
2.40.1
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