From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@au1.ibm.com>
Subject: Re: [PATCH 11/12] drm/ast: Fix test for VGA enabled
Date: Fri, 24 Feb 2017 10:24:02 +1100
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 <20170223225357.9572-11-benh@kernel.crashing.org>
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Cc: linuxppc-dev@ozlabs.org, "Y . C . Chen" <yc_chen@aspeedtech.com>, airlied@redhat.com
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On Fri, 2017-02-24 at 09:53 +1100, Benjamin Herrenschmidt wrote:
> From: "Y.C. Chen" <yc_chen@aspeedtech.com>
> 
> (Get better description from Aspeed)

And this should have been:

<<
The test to see if VGA was already enabled is doing an unnecessary
second test from a register that may or may not have been initialized
to a valid value. Remove it.
>>

If you prefer you can find the whole thing (already fixed up)
at git@github.com:ozbenh/linux-ast.git

Cheers,
Ben.

> Signed-off-by: Y.C. Chen <yc_chen@aspeedtech.com>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>  drivers/gpu/drm/ast/ast_post.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_post.c
> b/drivers/gpu/drm/ast/ast_post.c
> index c15f643..a5a7809 100644
> --- a/drivers/gpu/drm/ast/ast_post.c
> +++ b/drivers/gpu/drm/ast/ast_post.c
> @@ -59,13 +59,9 @@ bool ast_is_vga_enabled(struct drm_device *dev)
>  		/* TODO 1180 */
>  	} else {
>  		ch = ast_io_read8(ast, AST_IO_VGA_ENABLE_PORT);
> -		if (ch) {
> -			ast_open_key(ast);
> -			ch = ast_get_index_reg_mask(ast,
> AST_IO_CRTC_PORT, 0xb6, 0xff);
> -			return ch & 0x04;
> -		}
> +		return !!(ch & 0x01);
>  	}
> -	return 0;
> +	return false;
>  }
>  
>  static const u8 extreginfo[] = { 0x0f, 0x04, 0x1c, 0xff };