[PATCH 1/2] acpi/video: Load the module even if ACPI is disabled

[PATCH 1/2] acpi/video: Load the module even if ACPI is disabled

[Chris Wilson]

i915.ko depends upon the acpi/video.ko module and so refuses to load if
ACPI is disabled at runtime if for example the BIOS is broken beyond
repair. acpi/video provides an optional service for i915.ko and so we
should just allow the modules to load, but do no nothing in order to let
the machines boot correctly.

Reported-by: Bill Augur <bill-auger@programmer.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
---
 drivers/acpi/video.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index debd30917010..3b76aef79a1c 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -2176,6 +2176,16 @@ EXPORT_SYMBOL(acpi_video_unregister_backlight);
 
 static int __init acpi_video_init(void)
 {
+	/* Let the module load even if ACPI is disabled (e.g. due to
+	 * a broken BIOS) so that i915.ko can still be loaded on such
+	 * old systems without an AcpiOpRegion.
+	 *
+	 * acpi_video_register() will report -ENODEV later as well due
+	 * to acpi_disabled when i915.ko tries to register itself afterwards.
+	 */
+	if (acpi_disabled)
+		return 0;
+
 	dmi_check_system(video_dmi_table);
 
 	if (intel_opregion_present())
-- 
2.1.4

[PATCH 2/2] acpi/video: Propagate the error code for acpi_video_register

[Chris Wilson]

Report the actual error code from acpi_bus_register_driver(), it may
help future debugging (typically ENODEV as previously reported, but the
unusual cases are where it may help most).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/acpi/video.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 3b76aef79a1c..c9d5d060b970 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -2110,7 +2110,8 @@ static int __init intel_opregion_present(void)
 
 int acpi_video_register(void)
 {
-	int result = 0;
+	int ret;
+
 	if (register_count) {
 		/*
 		 * if the function of acpi_video_register is already called,
@@ -2122,9 +2123,9 @@ int acpi_video_register(void)
 	mutex_init(&video_list_lock);
 	INIT_LIST_HEAD(&video_bus_head);
 
-	result = acpi_bus_register_driver(&acpi_video_bus);
-	if (result < 0)
-		return -ENODEV;
+	ret = acpi_bus_register_driver(&acpi_video_bus);
+	if (ret)
+		return ret;
 
 	/*
 	 * When the acpi_video_bus is loaded successfully, increase
-- 
2.1.4

Re: [PATCH 1/2] acpi/video: Load the module even if ACPI is disabled

[Aaron Lu]

On Sun, Mar 01, 2015 at 10:41:37AM +0000, Chris Wilson wrote:
> i915.ko depends upon the acpi/video.ko module and so refuses to load if
> ACPI is disabled at runtime if for example the BIOS is broken beyond
> repair. acpi/video provides an optional service for i915.ko and so we
> should just allow the modules to load, but do no nothing in order to let
> the machines boot correctly.
> 
> Reported-by: Bill Augur <bill-auger@programmer.net>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Zhang Rui <rui.zhang@intel.com>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <lenb@kernel.org>
> Cc: linux-acpi@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: stable@vger.kernel.org

For both patches:
Acked-by: Aaron Lu <aaron.lu@intel.com>

Thanks,
Aaron

> ---
>  drivers/acpi/video.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index debd30917010..3b76aef79a1c 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -2176,6 +2176,16 @@ EXPORT_SYMBOL(acpi_video_unregister_backlight);
>  
>  static int __init acpi_video_init(void)
>  {
> +	/* Let the module load even if ACPI is disabled (e.g. due to
> +	 * a broken BIOS) so that i915.ko can still be loaded on such
> +	 * old systems without an AcpiOpRegion.
> +	 *
> +	 * acpi_video_register() will report -ENODEV later as well due
> +	 * to acpi_disabled when i915.ko tries to register itself afterwards.
> +	 */
> +	if (acpi_disabled)
> +		return 0;
> +
>  	dmi_check_system(video_dmi_table);
>  
>  	if (intel_opregion_present())
> -- 
> 2.1.4
> 
> --
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Re: [PATCH 1/2] acpi/video: Load the module even if ACPI is disabled

[Rafael J. Wysocki]

On Wednesday, March 04, 2015 09:55:55 AM Aaron Lu wrote:
> On Sun, Mar 01, 2015 at 10:41:37AM +0000, Chris Wilson wrote:
> > i915.ko depends upon the acpi/video.ko module and so refuses to load if
> > ACPI is disabled at runtime if for example the BIOS is broken beyond
> > repair. acpi/video provides an optional service for i915.ko and so we
> > should just allow the modules to load, but do no nothing in order to let
> > the machines boot correctly.
> > 
> > Reported-by: Bill Augur <bill-auger@programmer.net>
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Cc: Zhang Rui <rui.zhang@intel.com>
> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> > Cc: Len Brown <lenb@kernel.org>
> > Cc: linux-acpi@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: stable@vger.kernel.org
> 
> For both patches:
> Acked-by: Aaron Lu <aaron.lu@intel.com>

Both applied, thanks!


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.