From: Jani Nikula <jani.nikula@linux.intel.com>
To: daniel.vetter@intel.com, intel-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Subject: Re: [PATCH] drm/i915: fix build error without CONFIG_BACKLIGHT_CLASS_DEVICE
Date: Thu, 30 Mar 2017 09:49:21 +0300 [thread overview]
Message-ID: <87a88345u6.fsf@intel.com> (raw)
In-Reply-To: <20170329092722.6352-1-tobias.regnery@gmail.com>
On Wed, 29 Mar 2017, Tobias Regnery <tobias.regnery@gmail.com> wrote:
> With CONFIG_ACPI=n and CONFIG_BACKLIGHT_CLASS_DEVICE=n we see the following
> link error in the i915 driver:
>
> drivers/built-in.o: In function 'intel_backlight_device_register':
> (.text+0x2a921d): undefined reference to 'backlight_device_register'
>
> Fix this by removing the condition on ACPI from the appropriate select
> statement.
The right fix for the build problem is to add empty stub functions for
BACKLIGHT_CLASS_DEVICE=n in include/linux/backlight.h. I'm frankly
surprised nobody's done that yet.
It's another question whether we should support and select backlight for
ACPI=n, and yet another question whether we should support ACPI=n.
Also, selecting BACKLIGHT_CLASS_DEVICE is fundamentally broken, but
people aren't interested [1].
BR,
Jani.
[1] http://mid.mail-archive.com/1413580403-16225-1-git-send-email-jani.nikula@intel.com
>
> Signed-off-by: Tobias Regnery <tobias.regnery@gmail.com>
> ---
> drivers/gpu/drm/i915/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index a5cd5dacf055..532df4bb9283 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -15,7 +15,7 @@ config DRM_I915
> # i915 depends on ACPI_VIDEO when ACPI is enabled
> # but for select to work, need to select ACPI_VIDEO's dependencies, ick
> select BACKLIGHT_LCD_SUPPORT if ACPI
> - select BACKLIGHT_CLASS_DEVICE if ACPI
> + select BACKLIGHT_CLASS_DEVICE
> select INPUT if ACPI
> select ACPI_VIDEO if ACPI
> select ACPI_BUTTON if ACPI
--
Jani Nikula, Intel Open Source Technology Center
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WARNING: multiple messages have this Message-ID (diff)
From: Jani Nikula <jani.nikula@linux.intel.com>
To: Tobias Regnery <tobias.regnery@gmail.com>,
daniel.vetter@intel.com, intel-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Subject: Re: [PATCH] drm/i915: fix build error without CONFIG_BACKLIGHT_CLASS_DEVICE
Date: Thu, 30 Mar 2017 09:49:21 +0300 [thread overview]
Message-ID: <87a88345u6.fsf@intel.com> (raw)
In-Reply-To: <20170329092722.6352-1-tobias.regnery@gmail.com>
On Wed, 29 Mar 2017, Tobias Regnery <tobias.regnery@gmail.com> wrote:
> With CONFIG_ACPI=n and CONFIG_BACKLIGHT_CLASS_DEVICE=n we see the following
> link error in the i915 driver:
>
> drivers/built-in.o: In function 'intel_backlight_device_register':
> (.text+0x2a921d): undefined reference to 'backlight_device_register'
>
> Fix this by removing the condition on ACPI from the appropriate select
> statement.
The right fix for the build problem is to add empty stub functions for
BACKLIGHT_CLASS_DEVICE=n in include/linux/backlight.h. I'm frankly
surprised nobody's done that yet.
It's another question whether we should support and select backlight for
ACPI=n, and yet another question whether we should support ACPI=n.
Also, selecting BACKLIGHT_CLASS_DEVICE is fundamentally broken, but
people aren't interested [1].
BR,
Jani.
[1] http://mid.mail-archive.com/1413580403-16225-1-git-send-email-jani.nikula@intel.com
>
> Signed-off-by: Tobias Regnery <tobias.regnery@gmail.com>
> ---
> drivers/gpu/drm/i915/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index a5cd5dacf055..532df4bb9283 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -15,7 +15,7 @@ config DRM_I915
> # i915 depends on ACPI_VIDEO when ACPI is enabled
> # but for select to work, need to select ACPI_VIDEO's dependencies, ick
> select BACKLIGHT_LCD_SUPPORT if ACPI
> - select BACKLIGHT_CLASS_DEVICE if ACPI
> + select BACKLIGHT_CLASS_DEVICE
> select INPUT if ACPI
> select ACPI_VIDEO if ACPI
> select ACPI_BUTTON if ACPI
--
Jani Nikula, Intel Open Source Technology Center
next prev parent reply other threads:[~2017-03-30 6:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 9:27 [PATCH] drm/i915: fix build error without CONFIG_BACKLIGHT_CLASS_DEVICE Tobias Regnery
2017-03-30 6:49 ` Jani Nikula [this message]
2017-03-30 6:49 ` Jani Nikula
2017-03-31 6:35 ` Tobias Regnery
2017-03-31 6:35 ` Tobias Regnery
2017-03-30 9:43 ` ✗ Fi.CI.BAT: warning for " Patchwork
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