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Message-ID: <4364d453-3560-c3c2-15b1-146f9578755b@infradead.org>
Date:   Tue, 12 Sep 2023 07:52:21 -0700
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Subject: Re: linux-next: Tree for Sep 11
 (drivers/gpu/drm/i915/display/intel_backlight.o)
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To:     Jani Nikula <jani.nikula@linux.intel.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Linux Next Mailing List <linux-next@vger.kernel.org>
Cc:     intel-gfx@lists.freedesktop.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>
References: <20230911121131.006d3fec@canb.auug.org.au>
 <eac933bb-eb6d-8b21-422a-b8c6255facc3@infradead.org>
 <87a5tresu8.fsf@intel.com>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <87a5tresu8.fsf@intel.com>
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On 9/12/23 00:47, Jani Nikula wrote:
> On Mon, 11 Sep 2023, Randy Dunlap <rdunlap@infradead.org> wrote:
>> On 9/10/23 19:11, Stephen Rothwell wrote:
>>> Hi all,
>>>
>>> Please do *not* include material destined for v6.7 in your linux-next
>>> included branches until *after* v6.6-rc1 has been released.  Also,
>>> do *not* rebase your linu-next included branches onto v6.5.
>>>
>>> Changes since 20230908:
>>>
>>> Non-merge commits (relative to Linus' tree): 643
>>>  614 files changed, 227990 insertions(+), 9502 deletions(-)
>>>
>>> ----------------------------------------------------------------------------
>>
>> on x86_64:
>>
>> # CONFIG_ACPI is not set
>> CONFIG_DRM_I915=y
>> CONFIG_BACKLIGHT_CLASS_DEVICE=m
>>
>> I915 selects BACKLIGHT_CLASS_DEVICE if ACPI is set.
>>
>> ld: drivers/gpu/drm/i915/display/intel_backlight.o: in function `intel_backlight_device_register':
>> intel_backlight.c:(.text+0x4988): undefined reference to `backlight_device_get_by_name'
>> ld: intel_backlight.c:(.text+0x4a1b): undefined reference to `backlight_device_register'
>> ld: drivers/gpu/drm/i915/display/intel_backlight.o: in function `intel_backlight_device_unregister':
>> intel_backlight.c:(.text+0x4b56): undefined reference to `backlight_device_unregister'
> 
> This comes up periodically. The fix is for i915 to depend on backlight,
> but it's not possible to fix just i915, as it'll lead to circular deps
> unless *all* select backlight is switched to depend on backlight.
> 
> I've gone through it once [1], and not keen on doing it again unless
> there's buy-in.
> 
> IS_REACHABLE() is often suggested as a workaround, but I think it's just
> plain wrong. i915=y backlight=m is not a configuration that makes
> sense. Kernel configuration is hard enough, there's no point in allowing
> dumb configs that just silently don't work.
> 

Yes, IS_REACHABLE() is just fugly nonsense.

Thanks for the reminder of your attempt(s).

> 
> BR,
> Jani.
> 
> 
> [1] https://lore.kernel.org/r/1413580403-16225-1-git-send-email-jani.nikula@intel.com
> 
> 
> 

-- 
~Randy