linux-kernel - [PATCH] PCI/sysfs: hide boot_display definition when VIDEO=n

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Message-ID: <20250721210248.267962-1-rdunlap@infradead.org>
Date: Mon, 21 Jul 2025 14:02:37 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: linux-kernel@...r.kernel.org
Cc: Randy Dunlap <rdunlap@...radead.org>,
	Mario Limonciello <mario.limonciello@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org
Subject: [PATCH] PCI/sysfs: hide boot_display definition when VIDEO=n

When CONFIG_VIDEO is not set, defining the 'boot_display' attribute
causes build errors/warnings, so hide the declaration as is done with
other code that uses this variable. Bracket unused code inside
#ifdef CONFIG_VIDEO/#endif to prevent other build warnings/errors.

include/linux/device.h:199:33: warning: 'dev_attr_boot_display' defined but not used [-Wunused-variable]
  199 |         struct device_attribute dev_attr_##_name = __ATTR_RO(_name)
drivers/pci/pci-sysfs.c:688:8: note: in expansion of macro 'DEVICE_ATTR_RO'
  688 | static DEVICE_ATTR_RO(boot_display);

drivers/pci/pci-sysfs.c:683:16: warning: ‘boot_display_show’ defined but not used [-Wunused-function]
  683 | static ssize_t boot_display_show(struct device *dev,
      |                ^~~~~~~~~~~~~~~~~

Fixes: c4f2dc1e5293c ("PCI: Add a new 'boot_display' attribute")
Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
---
Cc: Mario Limonciello <mario.limonciello@....com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: linux-pci@...r.kernel.org

Also, a question:
What does this do in pci-sysfs.c?
#ifndef ARCH_PCI_DEV_GROUPS
#define ARCH_PCI_DEV_GROUPS
#endif
Is there some hidden macro (probably using string concatenation)
that uses this define value? Thanks.

 drivers/pci/pci-sysfs.c |    3 +++
 1 file changed, 3 insertions(+)

--- linux-next-20250721.orig/drivers/pci/pci-sysfs.c
+++ linux-next-20250721/drivers/pci/pci-sysfs.c
@@ -680,12 +680,15 @@ const struct attribute_group *pcibus_gro
 	NULL,
 };
 
+#ifdef CONFIG_VIDEO
 static ssize_t boot_display_show(struct device *dev,
 				 struct device_attribute *attr, char *buf)
 {
 	return sysfs_emit(buf, "1\n");
 }
+
 static DEVICE_ATTR_RO(boot_display);
+#endif
 
 static ssize_t boot_vga_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)