[PATCH] drm/amd/display: Determine IPS mode by ASIC and PMFW versions

[sunpeng.li at amd.com]

From: Leo Li <sunpeng.li at amd.com>

[Why]

DCN IPS interoperates with other system idle power features, such as
Zstates.

On DCN35, there is a known issue where system Z8 + DCN IPS2 causes a
hard hang. We observe this on systems where the SBIOS allows Z8.

Though there is a SBIOS fix, there's no guarantee that users will get it
any time soon, or even install it. A workaround is needed to prevent
this from rearing its head in the wild.

[How]

For DCN35, check the pmfw version to determine whether the SBIOS has the
fix. If not, set IPS1+RCG as the deepest possible state in all cases
except for s0ix and display off (DPMS). Otherwise, enable all IPS

Signed-off-by: Leo Li <sunpeng.li at amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 26 ++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index a18ecf8607232..a2e4973a4f6e3 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1754,6 +1754,30 @@ static struct dml2_soc_bb *dm_dmub_get_vbios_bounding_box(struct amdgpu_device *
 	return bb;
 }
 
+static enum dmub_ips_disable_type dm_get_default_ips_mode(
+	struct amdgpu_device *adev)
+{
+	/*
+	 * 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 (amdgpu_ip_version(adev, DCE_HWIP, 0) == IP_VERSION(3, 5, 0) &&
+	    (adev->pm.fw_version & 0x00FFFF00) < 0x005D6300)
+		return DMUB_IPS_RCG_IN_ACTIVE_IPS2_IN_OFF;
+
+	if (amdgpu_ip_version(adev, DCE_HWIP, 0) >= IP_VERSION(3, 5, 0))
+		return DMUB_IPS_ENABLE;
+
+	/* ASICs older than DCN35 do not have IPSs */
+	return DMUB_IPS_DISABLE_ALL;
+}
+
 static int amdgpu_dm_init(struct amdgpu_device *adev)
 {
 	struct dc_init_data init_data;
@@ -1871,7 +1895,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	else if (amdgpu_dc_debug_mask & DC_FORCE_IPS_ENABLE)
 		init_data.flags.disable_ips = DMUB_IPS_ENABLE;
 	else
-		init_data.flags.disable_ips = DMUB_IPS_ENABLE;
+		init_data.flags.disable_ips = dm_get_default_ips_mode(adev);
 
 	init_data.flags.disable_ips_in_vpb = 0;
 
-- 
2.46.0