[PATCH v3] drm/i915: Fix lock dropping in intel_tv_detect()

[PATCH v3] drm/i915: Fix lock dropping in intel_tv_detect()

[ville.syrjala]

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

When intel_tv_detect() fails to do load detection it would forget to
drop the locks and clean up the acquire context. Fix it up.

This is a regression from:
 commit 208bf9fdcd3575aa4a5d48b3e0295f7cdaf6fc44
 Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
 Date:   Mon Aug 11 13:15:35 2014 +0300

    drm/i915: Fix locking for intel_enable_pipe_a()

v2: Make the code more readable (Chris)
v3: Drop WARN_ON(type < 0) (Chris)

Cc: stable@vger.kernel.org
Cc: Tibor Billes <tbilles@gmx.com>
Reported-by: Tibor Billes <tbilles@gmx.com>
Tested-by: Tibor Billes <tbilles@gmx.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_tv.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
index 32186a6..c69d3ce 100644
--- a/drivers/gpu/drm/i915/intel_tv.c
+++ b/drivers/gpu/drm/i915/intel_tv.c
@@ -1311,6 +1311,7 @@ intel_tv_detect(struct drm_connector *connector, bool force)
 {
 	struct drm_display_mode mode;
 	struct intel_tv *intel_tv = intel_attached_tv(connector);
+	enum drm_connector_status status;
 	int type;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
@@ -1328,16 +1329,19 @@ intel_tv_detect(struct drm_connector *connector, bool force)
 		if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
 			type = intel_tv_detect_type(intel_tv, connector);
 			intel_release_load_detect_pipe(connector, &tmp);
+			status = type < 0 ?
+				connector_status_disconnected :
+				connector_status_connected;
 		} else
-			return connector_status_unknown;
+			status = connector_status_unknown;
 
 		drm_modeset_drop_locks(&ctx);
 		drm_modeset_acquire_fini(&ctx);
 	} else
 		return connector->status;
 
-	if (type < 0)
-		return connector_status_disconnected;
+	if (status != connector_status_connected)
+		return status;
 
 	intel_tv->type = type;
 	intel_tv_find_better_format(connector);
-- 
1.8.5.5

Re: [PATCH v3] drm/i915: Fix lock dropping in intel_tv_detect()

[Jani Nikula]

On Tue, 02 Sep 2014, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> When intel_tv_detect() fails to do load detection it would forget to
> drop the locks and clean up the acquire context. Fix it up.
>
> This is a regression from:
>  commit 208bf9fdcd3575aa4a5d48b3e0295f7cdaf6fc44
>  Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
>  Date:   Mon Aug 11 13:15:35 2014 +0300
>
>     drm/i915: Fix locking for intel_enable_pipe_a()
>
> v2: Make the code more readable (Chris)
> v3: Drop WARN_ON(type < 0) (Chris)
>
> Cc: stable@vger.kernel.org
> Cc: Tibor Billes <tbilles@gmx.com>
> Reported-by: Tibor Billes <tbilles@gmx.com>
> Tested-by: Tibor Billes <tbilles@gmx.com>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Pushed to drm-intel-fixes, thanks for the patch, review, and testing.

BR,
Jani.


> ---
>  drivers/gpu/drm/i915/intel_tv.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> index 32186a6..c69d3ce 100644
> --- a/drivers/gpu/drm/i915/intel_tv.c
> +++ b/drivers/gpu/drm/i915/intel_tv.c
> @@ -1311,6 +1311,7 @@ intel_tv_detect(struct drm_connector *connector, bool force)
>  {
>  	struct drm_display_mode mode;
>  	struct intel_tv *intel_tv = intel_attached_tv(connector);
> +	enum drm_connector_status status;
>  	int type;
>  
>  	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
> @@ -1328,16 +1329,19 @@ intel_tv_detect(struct drm_connector *connector, bool force)
>  		if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
>  			type = intel_tv_detect_type(intel_tv, connector);
>  			intel_release_load_detect_pipe(connector, &tmp);
> +			status = type < 0 ?
> +				connector_status_disconnected :
> +				connector_status_connected;
>  		} else
> -			return connector_status_unknown;
> +			status = connector_status_unknown;
>  
>  		drm_modeset_drop_locks(&ctx);
>  		drm_modeset_acquire_fini(&ctx);
>  	} else
>  		return connector->status;
>  
> -	if (type < 0)
> -		return connector_status_disconnected;
> +	if (status != connector_status_connected)
> +		return status;
>  
>  	intel_tv->type = type;
>  	intel_tv_find_better_format(connector);
> -- 
> 1.8.5.5
>

-- 
Jani Nikula, Intel Open Source Technology Center