drm/i915/display: add module parameter to enable DMC wakelock

This feature should be disabled by default until properly tested and
mature.  Add a module parameter to enable the feature for testing,
while keeping it disabled by default for now.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412094148.808179-4-luciano.coelho@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_display_params.c

@@ -116,6 +116,11 @@ intel_display_param_named_unsafe(enable_psr2_sel_fetch, bool, 0400,
 	"(0=disabled, 1=enabled) "
 	"Default: 1");
 
+intel_display_param_named_unsafe(enable_dmc_wl, bool, 0400,
+	"Enable DMC wakelock "
+	"(0=disabled, 1=enabled) "
+	"Default: 0");
+
 __maybe_unused
 static void _param_print_bool(struct drm_printer *p, const char *driver_name,
 			      const char *name, bool val)

drivers/gpu/drm/i915/display/intel_display_params.h

@@ -46,6 +46,7 @@ struct drm_i915_private;
 	param(int, enable_psr, -1, 0600) \
 	param(bool, psr_safest_params, false, 0400) \
 	param(bool, enable_psr2_sel_fetch, true, 0400) \
+	param(bool, enable_dmc_wl, false, 0400) \
 
 #define MEMBER(T, member, ...) T member;
 struct intel_display_params {

drivers/gpu/drm/i915/display/intel_dmc_wl.c

@@ -109,7 +109,8 @@ static bool intel_dmc_wl_check_range(u32 address)
 static bool __intel_dmc_wl_supported(struct drm_i915_private *i915)
 {
 	if (DISPLAY_VER(i915) < 20 ||
-	    !intel_dmc_has_payload(i915))
+	    !intel_dmc_has_payload(i915) ||
+	    !i915->display.params.enable_dmc_wl)
 		return false;
 
 	return true;
@@ -120,7 +121,8 @@ void intel_dmc_wl_init(struct drm_i915_private *i915)
 	struct intel_dmc_wl *wl = &i915->display.wl;
 
 	/* don't call __intel_dmc_wl_supported(), DMC is not loaded yet */
-	if (DISPLAY_VER(i915) < 20)
+	if (DISPLAY_VER(i915) < 20 ||
+	    !i915->display.params.enable_dmc_wl)
 		return;
 
 	INIT_DELAYED_WORK(&wl->work, intel_dmc_wl_work);