[PATCH] drm/i915: Cache max number of pipes

[Mika Kahola]

CI system spotted an error on CFL system when running IGT tests with
display disabled. In this case, the 'INTEL_INFO(dev_priv)->num_pipes'
is set to 0. This will cause that we prematurely return from
'get_saved_enc()'.

To fix this issue, the patch introduces a 'max_pipes' variable which caches
the maximum number of available pipes.

Reference: https://bugs.freedesktop.org/show_bug.cgi?id=103206
Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h          | 1 +
 drivers/gpu/drm/i915/intel_audio.c       | 2 +-
 drivers/gpu/drm/i915/intel_device_info.c | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 770305b..6229ff8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -868,6 +868,7 @@ struct intel_device_info {
 	u8 num_pipes;
 	u8 num_sprites[I915_MAX_PIPES];
 	u8 num_scalers[I915_MAX_PIPES];
+	u8 max_pipes;
 
 	unsigned int page_sizes; /* page sizes supported by the HW */
 
diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index 0ddba16..147bd3d 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -754,7 +754,7 @@ static struct intel_encoder *get_saved_enc(struct drm_i915_private *dev_priv,
 {
 	struct intel_encoder *encoder;
 
-	if (WARN_ON(pipe >= INTEL_INFO(dev_priv)->num_pipes))
+	if (WARN_ON(pipe >= INTEL_INFO(dev_priv)->max_pipes))
 		return NULL;
 
 	/* MST */
diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
index 875d428..ba1a807 100644
--- a/drivers/gpu/drm/i915/intel_device_info.c
+++ b/drivers/gpu/drm/i915/intel_device_info.c
@@ -376,6 +376,8 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
 			info->num_sprites[pipe] = 1;
 	}
 
+	info->max_pipes = info->num_pipes;
+
 	if (i915_modparams.disable_display) {
 		DRM_INFO("Display disabled (module parameter)\n");
 		info->num_pipes = 0;
-- 
2.7.4