linux-kernel - Re: [PATCH] efifb: Skip DMI checks if the bootloader knows what it's doing

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Date:	Fri, 27 Apr 2012 13:37:37 -0400
From:	Peter Jones <pjones@...hat.com>
To:	Matthew Garrett <mjg@...hat.com>
CC:	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] efifb: Skip DMI checks if the bootloader knows what it's
 doing

On 04/27/2012 10:54 AM, Matthew Garrett wrote:
> The majority of the DMI checks in efifb are for cases where the bootloader
> has provided invalid information. However, on some machines the overrides
> may do more harm than good due to configuration differences between machines
> with the same machine identifier. It turns out that it's possible for the
> bootloader to get the correct information on GOP-based systems, but we
> can't guarantee that the kernel's being booted with one that's been updated
> to do so. Add support for a capabilities flag that can be set by the
> bootloader, and skip the DMI checks in that case.
>
> Signed-off-by: Matthew Garrett<mjg@...hat.com>

Looks right to me.

Acked-by: Peter Jones <pjones@...hat.com>

> ---
>   drivers/video/efifb.c       |    4 +++-
>   include/linux/screen_info.h |    2 ++
>   2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c
> index b4a632a..932abaa 100644
> --- a/drivers/video/efifb.c
> +++ b/drivers/video/efifb.c
> @@ -553,7 +553,9 @@ static int __init efifb_init(void)
>   	int ret;
>   	char *option = NULL;
>
> -	dmi_check_system(dmi_system_table);
> +	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI ||
> +	    !(screen_info.capabilities&  VIDEO_CAPABILITY_SKIP_QUIRKS))
> +		dmi_check_system(dmi_system_table);
>
>   	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
>   		return -ENODEV;
> diff --git a/include/linux/screen_info.h b/include/linux/screen_info.h
> index 899fbb4..fb3c5a8 100644
> --- a/include/linux/screen_info.h
> +++ b/include/linux/screen_info.h
> @@ -68,6 +68,8 @@ struct screen_info {
>
>   #define VIDEO_FLAGS_NOCURSOR	(1<<  0) /* The video mode has no cursor set */
>
> +#define VIDEO_CAPABILITY_SKIP_QUIRKS	(1<<  0)
> +
>   #ifdef __KERNEL__
>   extern struct screen_info screen_info;
>


-- 
         Peter

Any connection between your reality and mine is purely coincidental.

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