[PATCH] drm/i915: Prevent a machine hang by checking crtc->active before loading lut

[PATCH] drm/i915: Prevent a machine hang by checking crtc->active before loading lut

[Chris Wilson]

From: Alban Browaeys <prahal@yahoo.com>

Before loading the lut (gamma), check the active state of intel_crtc,
otherwise at least on gen2 hang ensue.

This is reproducible in Xorg via:
  xset dpms force off
then
  xgamma -rgamma 2.0 # freeze.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44505
Signed-off-by: Alban Browaeys <prahal@yahoo.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
---
 drivers/gpu/drm/i915/intel_display.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cdcf99b..4b48de5 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6268,7 +6268,7 @@ void intel_crtc_load_lut(struct drm_crtc *crtc)
 	int i;
 
 	/* The clocks have to be on to load the palette. */
-	if (!crtc->enabled)
+	if (!crtc->enabled || !intel_crtc->active)
 		return;
 
 	/* use legacy palette for Ironlake */
-- 
1.7.9.1

Re: [PATCH] drm/i915: Prevent a machine hang by checking crtc->active before loading lut

[Jesse Barnes]

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On Fri, 24 Feb 2012 17:12:45 +0000
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> From: Alban Browaeys <prahal@yahoo.com>
> 
> Before loading the lut (gamma), check the active state of intel_crtc,
> otherwise at least on gen2 hang ensue.
> 
> This is reproducible in Xorg via:
>   xset dpms force off
> then
>   xgamma -rgamma 2.0 # freeze.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44505
> Signed-off-by: Alban Browaeys <prahal@yahoo.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: stable@kernel.org
> ---
>  drivers/gpu/drm/i915/intel_display.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index cdcf99b..4b48de5 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6268,7 +6268,7 @@ void intel_crtc_load_lut(struct drm_crtc *crtc)
>  	int i;
>  
>  	/* The clocks have to be on to load the palette. */
> -	if (!crtc->enabled)
> +	if (!crtc->enabled || !intel_crtc->active)
>  		return;
>  
>  	/* use legacy palette for Ironlake */

Yeah seems reasonable, thanks Chris.

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

-- 
Jesse Barnes, Intel Open Source Technology Center

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