drm/amd/display: Default IPS to RCG_IN_ACTIVE_IPS2_IN_OFF

[Why]

Recent findings show negligible power savings between IPS2 and RCG
during static desktop. In fact, DCN related clocks are higher
when IPS2 is enabled vs RCG.

RCG_IN_ACTIVE is also the default policy for another OS supported by
DC, and it has faster entry/exit.

[How]

Remove previous logic that checked for IPS2 support, and just default
to `DMUB_IPS_RCG_IN_ACTIVE_IPS2_IN_OFF`.

Fixes: 199888a ("drm/amd/display: Update IPS default mode for DCN35/DCN351")
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 8f772d7)
Cc: stable@vger.kernel.org

Author: leo-sunli1

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1920,26 +1920,6 @@ static enum dmub_ips_disable_type dm_get_default_ips_mode(
 	switch (amdgpu_ip_version(adev, DCE_HWIP, 0)) {
 	case IP_VERSION(3, 5, 0):
 	case IP_VERSION(3, 6, 0):
-		/*
-		 * On DCN35 systems with Z8 enabled, it's possible for IPS2 + Z8 to
-		 * cause a hard hang. A fix exists for newer PMFW.
-		 *
-		 * As a workaround, for non-fixed PMFW, force IPS1+RCG as the deepest
-		 * IPS state in all cases, except for s0ix and all displays off (DPMS),
-		 * where IPS2 is allowed.
-		 *
-		 * When checking pmfw version, use the major and minor only.
-		 */
-		if ((adev->pm.fw_version & 0x00FFFF00) < 0x005D6300)
-			ret = DMUB_IPS_RCG_IN_ACTIVE_IPS2_IN_OFF;
-		else if (amdgpu_ip_version(adev, GC_HWIP, 0) > IP_VERSION(11, 5, 0))
-			/*
-			 * Other ASICs with DCN35 that have residency issues with
-			 * IPS2 in idle.
-			 * We want them to use IPS2 only in display off cases.
-			 */
-			ret =  DMUB_IPS_RCG_IN_ACTIVE_IPS2_IN_OFF;
-		break;
 	case IP_VERSION(3, 5, 1):
 		ret =  DMUB_IPS_RCG_IN_ACTIVE_IPS2_IN_OFF;
 		break;