drm/intel: add enable_psr module option and disable psr by default

v2: prefer seq_puts to seq_printf detected by Paulo Zanoni.
v3: PSR is disabled by default. Without userspace ready it
    will cause regression for kde and xdm users

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Shobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1565,6 +1565,9 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
 		case PSR_NO_SINK:
 			seq_puts(m, "not supported by panel");
 			break;
+		case PSR_MODULE_PARAM:
+			seq_puts(m, "disabled by flag");
+			break;
 		case PSR_CRTC_NOT_ACTIVE:
 			seq_puts(m, "crtc not active");
 			break;

drivers/gpu/drm/i915/i915_drv.c

@@ -118,6 +118,10 @@ module_param_named(i915_enable_ppgtt, i915_enable_ppgtt, int, 0600);
 MODULE_PARM_DESC(i915_enable_ppgtt,
 		"Enable PPGTT (default: true)");
 
+int i915_enable_psr __read_mostly = 0;
+module_param_named(enable_psr, i915_enable_psr, int, 0600);
+MODULE_PARM_DESC(enable_psr, "Enable PSR (default: false)");
+
 unsigned int i915_preliminary_hw_support __read_mostly = 0;
 module_param_named(preliminary_hw_support, i915_preliminary_hw_support, int, 0600);
 MODULE_PARM_DESC(preliminary_hw_support,

drivers/gpu/drm/i915/i915_drv.h

@@ -596,6 +596,7 @@ struct i915_fbc {
 enum no_psr_reason {
 	PSR_NO_SOURCE, /* Not supported on platform */
 	PSR_NO_SINK, /* Not supported by panel */
+	PSR_MODULE_PARAM,
 	PSR_CRTC_NOT_ACTIVE,
 	PSR_PWR_WELL_ENABLED,
 	PSR_NOT_TILED,
@@ -1621,6 +1622,7 @@ extern int i915_enable_rc6 __read_mostly;
 extern int i915_enable_fbc __read_mostly;
 extern bool i915_enable_hangcheck __read_mostly;
 extern int i915_enable_ppgtt __read_mostly;
+extern int i915_enable_psr __read_mostly;
 extern unsigned int i915_preliminary_hw_support __read_mostly;
 extern int i915_disable_power_well __read_mostly;
 extern int i915_enable_ips __read_mostly;

drivers/gpu/drm/i915/intel_dp.c

@@ -1521,6 +1521,12 @@ static bool intel_edp_psr_match_conditions(struct intel_dp *intel_dp)
 		return false;
 	}
 
+	if (!i915_enable_psr) {
+		DRM_DEBUG_KMS("PSR disable by flag\n");
+		dev_priv->no_psr_reason = PSR_MODULE_PARAM;
+		return false;
+	}
+
 	if (!intel_crtc->active || !crtc->fb || !crtc->mode.clock) {
 		DRM_DEBUG_KMS("crtc not active for PSR\n");
 		dev_priv->no_psr_reason = PSR_CRTC_NOT_ACTIVE;