linux-kernel - [PATCH v3] of: Make of framebuffer devices unique

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Date:   Fri, 20 Jan 2023 19:09:57 +0100
From:   Michal Suchanek <msuchanek@...e.de>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Michal Suchanek <msuchanek@...e.de>,
        "Erhard F." <erhard_f@...lbox.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
        <devicetree@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        open list <linux-kernel@...r.kernel.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3] of: Make of framebuffer devices unique

Since Linux 5.19 this error is observed:

sysfs: cannot create duplicate filename '/devices/platform/of-display'

This is because multiple devices with the same name 'of-display' are
created on the same bus.

Update the code to create numbered device names for the non-boot
disaplay.

cc: linuxppc-dev@...ts.ozlabs.org
References: https://bugzilla.kernel.org/show_bug.cgi?id=216095
Fixes: 52b1b46c39ae ("of: Create platform devices for OF framebuffers")
Reported-by: Erhard F. <erhard_f@...lbox.org>
Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
Signed-off-by: Michal Suchanek <msuchanek@...e.de>
---
v3:
- merge fix into original patch
- Update the device name format
- add missing const
- do not continue with iterating display devices when formatting device
  name fails
---
 drivers/of/platform.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 81c8c227ab6b..4d3a4d9f79f2 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -525,6 +525,9 @@ static int __init of_platform_default_populate_init(void)
 	if (IS_ENABLED(CONFIG_PPC)) {
 		struct device_node *boot_display = NULL;
 		struct platform_device *dev;
+		int display_number = 0;
+		char buf[14];
+		const char *of_display_format = "of-display.%d";
 		int ret;
 
 		/* Check if we have a MacOS display without a node spec */
@@ -555,7 +558,10 @@ static int __init of_platform_default_populate_init(void)
 			if (!of_get_property(node, "linux,opened", NULL) ||
 			    !of_get_property(node, "linux,boot-display", NULL))
 				continue;
-			dev = of_platform_device_create(node, "of-display", NULL);
+			ret = snprintf(buf, sizeof(buf), of_display_format, display_number++);
+			if (ret >= sizeof(buf))
+				return -EOVERFLOW;
+			dev = of_platform_device_create(node, buf, NULL);
 			if (WARN_ON(!dev))
 				return -ENOMEM;
 			boot_display = node;
@@ -564,7 +570,10 @@ static int __init of_platform_default_populate_init(void)
 		for_each_node_by_type(node, "display") {
 			if (!of_get_property(node, "linux,opened", NULL) || node == boot_display)
 				continue;
-			of_platform_device_create(node, "of-display", NULL);
+			ret = snprintf(buf, sizeof(buf), of_display_format, display_number++);
+			if (ret >= sizeof(buf))
+				break;
+			of_platform_device_create(node, buf, NULL);
 		}
 
 	} else {
-- 
2.35.3