drm/i915: Initial implementation of PSR2 selective fetch

All GEN12 platforms supports PSR2 selective fetch but not all GEN12
platforms supports PSR2 hardware tracking(aka RKL).

This feature consists in software programming registers with the
damaged area of each plane this way hardware will only fetch from
memory those areas and sent the PSR2 selective update blocks to panel,
saving even more power.

But as initial step it is only enabling the full frame fetch at
every flip, the actual selective fetch part will come in a future
patch.

Also this is only handling the page flip side, it is still completely
missing frontbuffer modifications, that is why the
enable_psr2_sel_fetch parameter was added.

v3:
- calling intel_psr2_sel_fetch_update() during the atomic check phase
(Ville)

BSpec: 55229
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200810174144.76761-1-jose.souza@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/i915_params.c

@@ -102,6 +102,11 @@ i915_param_named(psr_safest_params, bool, 0400,
 	"is helpful to detect if PSR issues are related to bad values set in "
 	" VBT. (0=use VBT parameters, 1=use safest parameters)");
 
+i915_param_named_unsafe(enable_psr2_sel_fetch, bool, 0400,
+	"Enable PSR2 selective fetch "
+	"(0=disabled, 1=enabled) "
+	"Default: 0");
+
 i915_param_named_unsafe(force_probe, charp, 0400,
 	"Force probe the driver for specified devices. "
 	"See CONFIG_DRM_I915_FORCE_PROBE for details.");