drm/i915/psr: Allow PSR2 to be enabled when debugfs asks

For now PSR2 is still disabled by default for all platforms but is
our intention to let debugfs to enable it for debug and tests
proporses, so intel_psr2_enabled() that is also used by debugfs to
decide if PSR2 is going to be enabled needs to take in consideration
the debug field.

v2: Using the switch/case that intel_psr2_enabled() already had to
handle this(DK)

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190117205548.28378-1-jose.souza@intel.com

drivers/gpu/drm/i915/intel_psr.c

@@ -70,17 +70,17 @@ static bool psr_global_enabled(u32 debug)
 static bool intel_psr2_enabled(struct drm_i915_private *dev_priv,
 			       const struct intel_crtc_state *crtc_state)
 {
-	/* Disable PSR2 by default for all platforms */
-	if (i915_modparams.enable_psr == -1)
-		return false;
-
 	/* Cannot enable DSC and PSR2 simultaneously */
 	WARN_ON(crtc_state->dsc_params.compression_enable &&
 		crtc_state->has_psr2);
 
 	switch (dev_priv->psr.debug & I915_PSR_DEBUG_MODE_MASK) {
+	case I915_PSR_DEBUG_DISABLE:
 	case I915_PSR_DEBUG_FORCE_PSR1:
 		return false;
+	case I915_PSR_DEBUG_DEFAULT:
+		if (i915_modparams.enable_psr <= 0)
+			return false;
 	default:
 		return crtc_state->has_psr2;
 	}