[PATCH] drm/i915: Fix VGA_DISP_DISABLE check

[PATCH] drm/i915: Fix VGA_DISP_DISABLE check

[ville.syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The VGACNTRL register contains a bunch of other stuff besides
the VGA_DISP_DISABLE bit. When we write the register we always set those
other bits to zero, so normally the current check would work.

However on HSW disabling and re-enabling the power well will reset the
VGACNTRL register to its default value, which has several of the other
bits set as well.

So only look at the VGA_DISP_DISABLE bit when checking whether the VGA
plane needs re-disabling.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0ba0af4..925a387 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10659,7 +10659,7 @@ void i915_redisable_vga(struct drm_device *dev)
 	    (I915_READ(HSW_PWR_WELL_DRIVER) & HSW_PWR_WELL_STATE_ENABLED) == 0)
 		return;
 
-	if (I915_READ(vga_reg) != VGA_DISP_DISABLE) {
+	if (!(I915_READ(vga_reg) & VGA_DISP_DISABLE)) {
 		DRM_DEBUG_KMS("Something enabled VGA plane, disabling it\n");
 		i915_disable_vga(dev);
 		i915_disable_vga_mem(dev);
-- 
1.8.1.5

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Re: [PATCH] drm/i915: Fix VGA_DISP_DISABLE check

[Jesse Barnes]

On Fri,  4 Oct 2013 20:32:25 +0300
ville.syrjala@linux.intel.com wrote:

> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> The VGACNTRL register contains a bunch of other stuff besides
> the VGA_DISP_DISABLE bit. When we write the register we always set those
> other bits to zero, so normally the current check would work.
> 
> However on HSW disabling and re-enabling the power well will reset the
> VGACNTRL register to its default value, which has several of the other
> bits set as well.
> 
> So only look at the VGA_DISP_DISABLE bit when checking whether the VGA
> plane needs re-disabling.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 0ba0af4..925a387 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -10659,7 +10659,7 @@ void i915_redisable_vga(struct drm_device *dev)
>  	    (I915_READ(HSW_PWR_WELL_DRIVER) & HSW_PWR_WELL_STATE_ENABLED) == 0)
>  		return;
>  
> -	if (I915_READ(vga_reg) != VGA_DISP_DISABLE) {
> +	if (!(I915_READ(vga_reg) & VGA_DISP_DISABLE)) {
>  		DRM_DEBUG_KMS("Something enabled VGA plane, disabling it\n");
>  		i915_disable_vga(dev);
>  		i915_disable_vga_mem(dev);

Looks good.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center
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Re: [PATCH] drm/i915: Fix VGA_DISP_DISABLE check

[Daniel Vetter]

On Fri, Oct 04, 2013 at 11:07:19AM -0700, Jesse Barnes wrote:
> On Fri,  4 Oct 2013 20:32:25 +0300
> ville.syrjala@linux.intel.com wrote:
> 
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > The VGACNTRL register contains a bunch of other stuff besides
> > the VGA_DISP_DISABLE bit. When we write the register we always set those
> > other bits to zero, so normally the current check would work.
> > 
> > However on HSW disabling and re-enabling the power well will reset the
> > VGACNTRL register to its default value, which has several of the other
> > bits set as well.
> > 
> > So only look at the VGA_DISP_DISABLE bit when checking whether the VGA
> > plane needs re-disabling.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 0ba0af4..925a387 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -10659,7 +10659,7 @@ void i915_redisable_vga(struct drm_device *dev)
> >  	    (I915_READ(HSW_PWR_WELL_DRIVER) & HSW_PWR_WELL_STATE_ENABLED) == 0)
> >  		return;
> >  
> > -	if (I915_READ(vga_reg) != VGA_DISP_DISABLE) {
> > +	if (!(I915_READ(vga_reg) & VGA_DISP_DISABLE)) {
> >  		DRM_DEBUG_KMS("Something enabled VGA plane, disabling it\n");
> >  		i915_disable_vga(dev);
> >  		i915_disable_vga_mem(dev);
> 
> Looks good.
> 
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Queued for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch