Re: [PATCH 1/3] mach64: fix display corruption on big endian machines

["Ville Syrjälä" <syrjala@sci.fi>]

On Sat, Aug 25, 2018 at 03:51:00PM -0400, Mikulas Patocka wrote:
> The code for manual bit triple is not endian-clean. It builds the variable
> "hostdword" using byte accesses, therefore we must read the variable with
> "le32_to_cpu".
> 
> The patch also enables (hardware or software) bit triple only if the image
> is monochrome (image->depth). If we want to blit full-color image, we
> shouldn't use the triple code.

Makes sense.
Reviewed-by: Ville Syrjälä <syrjala@sci.fi>

> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Cc: stable@vger.kernel.org
> 
> ---
>  drivers/video/fbdev/aty/mach64_accel.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> Index: linux-stable/drivers/video/fbdev/aty/mach64_accel.c
> =================================> --- linux-stable.orig/drivers/video/fbdev/aty/mach64_accel.c	2018-08-24 17:31:21.000000000 +0200
> +++ linux-stable/drivers/video/fbdev/aty/mach64_accel.c	2018-08-24 19:12:40.000000000 +0200
> @@ -345,7 +345,7 @@ void atyfb_imageblit(struct fb_info *inf
>  		 * since Rage 3D IIc we have DP_HOST_TRIPLE_EN bit
>  		 * this hwaccelerated triple has an issue with not aligned data
>  		 */
> -		if (M64_HAS(HW_TRIPLE) && image->width % 8 = 0)
> +		if (image->depth = 1 && M64_HAS(HW_TRIPLE) && image->width % 8 = 0)
>  			pix_width |= DP_HOST_TRIPLE_EN;
>  	}
>  
> @@ -382,7 +382,7 @@ void atyfb_imageblit(struct fb_info *inf
>  	src_bytes = (((image->width * image->depth) + 7) / 8) * image->height;
>  
>  	/* manual triple each pixel */
> -	if (info->var.bits_per_pixel = 24 && !(pix_width & DP_HOST_TRIPLE_EN)) {
> +	if (image->depth = 1 && info->var.bits_per_pixel = 24 && !(pix_width & DP_HOST_TRIPLE_EN)) {
>  		int inbit, outbit, mult24, byte_id_in_dword, width;
>  		u8 *pbitmapin = (u8*)image->data, *pbitmapout;
>  		u32 hostdword;
> @@ -415,7 +415,7 @@ void atyfb_imageblit(struct fb_info *inf
>  				}
>  			}
>  			wait_for_fifo(1, par);
> -			aty_st_le32(HOST_DATA0, hostdword, par);
> +			aty_st_le32(HOST_DATA0, le32_to_cpu(hostdword), par);
>  		}
>  	} else {
>  		u32 *pbitmap, dwords = (src_bytes + 3) / 4;

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/