drm/i915/tgl: disable DDIC

The current SKUs added for Tiger Lake don't have DDIC hooked up, even
though it is supported by the SoC. The current state for these SKUs is
problematic since while enabling the combo phy, PORT_COMP_DW* return
0xFFFFFFFF, which is invalid per register definition.

During initialization we check what phys are not yet enabled by reading
PHY_MISC_C and try to enable it by toggling the "DE to IO Comp Pwr Down"
bit.  But after that any read to the PORT_COMP_DW* returns invalid
results. This removes the following warning

[56997.634353] Missing case (val == 4294967295)
[56997.639241] WARNING: CPU: 5 PID: 768 at drivers/gpu/drm/i915/display/intel_combo_phy.c:54 cnl_get_procmon_ref_values+0xc9/0xf0 [i915]
[56997.639808] Modules linked in: i915(+) prime_numbers x86_pkg_temp_thermal coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel e1000e [last unloaded: prime_numbers]
[56997.639808] CPU: 5 PID: 768 Comm: insmod Tainted: G     U  W         5.2.0-demarchi+ #65
[56997.639808] Hardware name: Intel Corporation Tiger Lake Client Platform/TigerLake U DDR4 SODIMM RVP, BIOS TGLSFWI1.R00.2252.A03.1906270154 06/27/2019
[56997.639808] RIP: 0010:cnl_get_procmon_ref_values+0xc9/0xf0 [i915]
[56997.639808] Code: 2c a0 85 c9 74 e0 81 f9 00 00 00 01 75 09 48 c7 c0 0c a4 2c a0 eb cf 48 c7 c6 3c 3a 31 a0 48 c7 c7 40 3a 31 a0 e8 6b 4d ea e0 <0f> 0b 48 c7 c0 00 a4 2c a0 eb b1 48 c7 c0 24 a4 2
c a0 eb a8 e8 be
[56997.639808] RSP: 0018:ffffc9000068f8a8 EFLAGS: 00010286
[56997.639808] RAX: 0000000000000000 RBX: ffff88848fa90000 RCX: 0000000000000000
[56997.639808] RDX: ffff8884a08b5ef8 RSI: ffff8884a08a6658 RDI: 00000000ffffffff
[56997.639808] RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
[56997.639808] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88848fa90000
[56997.639808] R13: 0000000000000000 R14: 0000000000000002 R15: 0006c00000162000
[56997.639808] FS:  00007f61ca3d12c0(0000) GS:ffff8884a0880000(0000) knlGS:0000000000000000
[56997.639808] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[56997.639808] CR2: 00007f71be6a92c0 CR3: 0000000494750006 CR4: 0000000000760ee0
[56997.639808] PKRU: 55555554
[56997.639808] Call Trace:
[56997.639808]  cnl_verify_procmon_ref_values+0x36/0xf0 [i915]
[56997.639808]  ? rcu_read_lock_sched_held+0x6f/0x80
[56997.639808]  ? gen11_fwtable_read32+0x257/0x290 [i915]
[56997.639808]  icl_combo_phy_verify_state.part.0+0x22/0xa0 [i915]
[56997.639808]  intel_combo_phy_init+0x17e/0x3e0 [i915]
[56997.639808]  ? icl_display_core_init+0x2c/0x1a0 [i915]
[56997.639808]  ? _raw_spin_unlock_irqrestore+0x4c/0x60
[56997.639808]  icl_display_core_init+0x34/0x1a0 [i915]
[56997.639808]  intel_power_domains_init_hw+0x200/0x570 [i915]
[56997.639808]  i915_driver_probe+0x103b/0x17e0 [i915]
[56997.639808]  ? printk+0x53/0x6a
[56997.639808]  i915_pci_probe+0x3b/0x190 [i915]

We may or may not need to change the implementation to account for DDIC
being available on other SKUs. For now I think the best thing to do is
to just disable the port.

Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190814235517.10032-1-lucas.demarchi@intel.com

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

@@ -6667,7 +6667,7 @@ bool intel_phy_is_combo(struct drm_i915_private *dev_priv, enum phy phy)
 	if (phy == PHY_NONE)
 		return false;
 
-	if (IS_ELKHARTLAKE(dev_priv) || INTEL_GEN(dev_priv) >= 12)
+	if (IS_ELKHARTLAKE(dev_priv))
 		return phy <= PHY_C;
 
 	if (INTEL_GEN(dev_priv) >= 11)
@@ -15299,7 +15299,6 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
 		/* TODO: initialize TC ports as well */
 		intel_ddi_init(dev_priv, PORT_A);
 		intel_ddi_init(dev_priv, PORT_B);
-		intel_ddi_init(dev_priv, PORT_C);
 		icl_dsi_init(dev_priv);
 	} else if (IS_ELKHARTLAKE(dev_priv)) {
 		intel_ddi_init(dev_priv, PORT_A);