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

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Message-ID: <8cecb2ac-9268-4294-b10d-35107479e675@infradead.org>
Date: Mon, 21 Jul 2025 14:08:22 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: "Limonciello, Mario" <Mario.Limonciello@....com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
 "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
 Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] PCI/sysfs: hide boot_display definition when VIDEO=n

Hi Mario,

On 7/21/25 2:05 PM, Limonciello, Mario wrote:
> On 7/21/25 4:02 PM, Randy Dunlap wrote:
>> 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>
> 
> Hi Randy,
> 
> Thanks for the patch.  Stephen raised this last week too and it's 
> brought up some other interesting topics as part of fixing it.
> 
> I have two other approaches on the mailing list right now waiting for 
> review.
> 
> 1) Make a static sysfs file.
> https://lore.kernel.org/linux-pci/20250721023818.2410062-1-superm1@kernel.org/T/#u
> 
> 2) Move out of PCI into DRM.
> https://lore.kernel.org/linux-pci/20250721185726.1264909-1-superm1@kernel.org/T/#me4356b3a172cbdafe83393bedce10f17a86e0da7

Yes, I found the second one just after I sent the patch.
Anyway, my patch is not relevant now.

Thanks.

-- 
~Randy