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

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Message-ID: <20150304015443.GA6943@aaronlu.sh.intel.com>
Date:	Wed, 4 Mar 2015 09:55:55 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	intel-gfx@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jani Nikula <jani.nikula@...el.com>,
	Zhang Rui <rui.zhang@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/2] acpi/video: Load the module even if ACPI is disabled

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@...grammer.net>
> Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> Cc: Jani Nikula <jani.nikula@...el.com>
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Len Brown <lenb@...nel.org>
> Cc: linux-acpi@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: stable@...r.kernel.org

For both patches:
Acked-by: Aaron Lu <aaron.lu@...el.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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