drm/amd/display: Enable Dynamic DTBCLK Switch

[WHAT]
Since dcn35, DTBCLK can be disabled when no DP2 sink connected for
power saving purpose.

Cc: Mario Limonciello <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: [email protected]
Reviewed-by: Aurabindo Pillai <[email protected]>
Signed-off-by: Fangzhi Zuo <[email protected]>
Signed-off-by: Alex Hung <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Fangzhi Zuo

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

@@ -2000,6 +2000,10 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 
 	init_data.flags.disable_ips_in_vpb = 0;
 
+	/* DCN35 and above supports dynamic DTBCLK switch */
+	if (amdgpu_ip_version(adev, DCE_HWIP, 0) >= IP_VERSION(3, 5, 0))
+		init_data.flags.allow_0_dtb_clk = true;
+
 	/* Enable DWB for tested platforms only */
 	if (amdgpu_ip_version(adev, DCE_HWIP, 0) >= IP_VERSION(3, 0, 0))
 		init_data.num_virtual_links = 1;