[Openchrome-devel] [PATCH 2/2] via: Add missing magic value to IGA1 fetch count

[James Simmons]

On Thu, 16 Aug 2012, Ondrej Zary wrote:

> Fetch count for IGA1 is missing magic "+4" that is called
> IGA1_FETCH_COUNT_PATCH_VALUE in viafb. This causes screen to be distorted
> at least on K8M890CE.

Yep, I'm missing that fetch count macro. Their is more brokeness than 
that. The fetch register is dependent on the resolution change (done by 
mode_set) and/or the color depth change (set_base). Currently the fetch 
register is update when the resolution is changed. If the color depth only 
changes the fecth register is not updated so it distorts the display as 
well. I will attempt to create a patch to address this. Thanks for 
pointing this out.

 
> Signed-off-by: Ondrej Zary <linux at rainbow-software.org>
> 
> --- a/drivers/gpu/drm/via/via_display.c
> +++ b/drivers/gpu/drm/via/via_display.c
> @@ -784,7 +784,8 @@ via_iga1_mode_set_base_atomic(struct drm_crtc *crtc, 
> struct drm_framebuffer *fb,
>  
>  	/* Load Fetch registers */
>  	pitch = ALIGN((crtc->mode.hdisplay * fb->bits_per_pixel >> 3), 16) >> 4;
> -	load_value_to_registers(VGABASE, &iga->fetch, pitch);
> +	/* magic "+4" is from viafb IGA1_FETCH_COUNT_PATCH_VALUE */
> +	load_value_to_registers(VGABASE, &iga->fetch, pitch + 4);
>  
>  	if ((state == ENTER_ATOMIC_MODE_SET) ||
>  	     crtc->fb->pitches[0] != fb->pitches[0]) {
> 
> -- 
> Ondrej Zary
> 
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