drm/i915/dgfx, mtl+: Disable display functionality if the display is not present

DG1/DG2 and MTL+ has added a new display-present HW flag. Check this
flag and if cleared, disable the driver's display functionality.

So far the missing check resulted in running the display initialization
sequence, and the WARNs below, due to the display register accesses
timing out:

[    3.902843] ------------[ cut here ]------------
[    3.902848] i915 0000:03:00.0: drm_WARN_ON(intel_de_wait_for_set(dev_priv, ((const i915_reg_t){ .reg = (0x42000) }), (1 << (27 - (pg))), 1))
[    3.902879] WARNING: CPU: 6 PID: 462 at drivers/gpu/drm/i915/display/intel_display_power_well.c:326 gen9_wait_for_power_well_fuses+0x71/0x80 [i915]
[    3.903009] Modules linked in: hid_sensor_hub intel_ishtp_hid i915(+) rtsx_pci_sdmmc drm_buddy mmc_core drm_display_helper crct10dif_pclmul nvme cec crc32_pclmul intel_ish_ipc crc32c_intel ucsi_acpi hid_multitouch nvme_core ghash_clmulni_intel typec_ucsi rtsx_pci ttm sha512_ssse3 serio_raw intel_ishtp typec video i2c_hid_acpi i2c_hid wmi pinctrl_tigerlake ip6_tables ip_tables x_tables fuse
[    3.903021] CPU: 6 PID: 462 Comm: systemd-udevd Tainted: G     U             6.2.0-rc6+ #50
[    3.903023] Hardware name: LENOVO 82VB/LNVNB161216, BIOS KMCN09WW 04/26/2022
[    3.903023] RIP: 0010:gen9_wait_for_power_well_fuses+0x71/0x80 [i915]
[    3.903105] Code: 48 8b 5f 50 48 85 db 75 03 48 8b 1f e8 98 bb 0d e9 48 c7 c1 00 65 a1 c0 48 89 da 48 c7 c7 4b c5 a3 c0 48 89 c6 e8 e3 df 53 e9 <0f> 0b 5b c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90
[    3.903106] RSP: 0018:ffffa7cec0b07a98 EFLAGS: 00010292
[    3.903107] RAX: 0000000000000080 RBX: ffff9a05430eaaa0 RCX: 0000000000000000
[    3.903108] RDX: 0000000000000001 RSI: ffffffffaa7ab69e RDI: 00000000ffffffff
[    3.903108] RBP: ffff9a0552ba2020 R08: ffffffffab062ce0 R09: 00000000abd3ffc2
[    3.903109] R10: ffffffffffffffff R11: 0000000000000081 R12: 0000000000000000
[    3.903109] R13: ffff9a05532a9cb0 R14: ffffffffc09e1670 R15: ffff9a0543132000
[    3.903110] FS:  00007f24d0fe5b40(0000) GS:ffff9a0ccf780000(0000) knlGS:0000000000000000
[    3.903110] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    3.903111] CR2: 00005643d7a31a28 CR3: 0000000111614002 CR4: 0000000000770ee0
[    3.903112] PKRU: 55555554
[    3.903112] Call Trace:
[    3.903113]  <TASK>
[    3.903114]  hsw_power_well_enable+0x12f/0x1a0 [i915]
[    3.903191]  intel_power_well_enable+0x21/0x70 [i915]
[    3.903265]  icl_display_core_init+0x92/0x6a0 [i915]
[    3.903346]  intel_power_domains_init_hw+0x1da/0x5b0 [i915]
[    3.903422]  intel_modeset_init_noirq+0x60/0x250 [i915]
[    3.903497]  i915_driver_probe+0x562/0xe10 [i915]
[    3.903557]  ? i915_pci_probe+0x87/0x180 [i915]
[    3.903617]  local_pci_probe+0x3e/0x80
[    3.903621]  pci_device_probe+0xb3/0x210
[    3.903622]  really_probe+0xdb/0x380
[    3.903624]  ? pm_runtime_barrier+0x50/0x90
[    3.903626]  __driver_probe_device+0x78/0x170
[    3.903627]  driver_probe_device+0x1f/0x90
[    3.903628]  __driver_attach+0xce/0x1c0
[    3.903629]  ? __pfx___driver_attach+0x10/0x10
[    3.903630]  bus_for_each_dev+0x5f/0x90
[    3.903631]  bus_add_driver+0x1ae/0x200
[    3.903632]  driver_register+0x89/0xe0
[    3.903634]  i915_init+0x1f/0x7f [i915]
[    3.903695]  ? __pfx_init_module+0x10/0x10 [i915]
[    3.903751]  do_one_initcall+0x43/0x220
[    3.903753]  ? kmalloc_trace+0x26/0x90
[    3.903756]  do_init_module+0x4a/0x200
[    3.903758]  __do_sys_init_module+0x157/0x180
[    3.903760]  do_syscall_64+0x58/0xc0
[    3.903762]  ? do_syscall_64+0x67/0xc0
[    3.903762]  ? exc_page_fault+0x70/0x170
[    3.903764]  entry_SYSCALL_64_after_hwframe+0x72/0xdc

Bspec: 49189, 53112

v2: (Jani)
- Change "Display fused off" dmesg info to "Display not present".
- Zero only runtime->pipe_mask, other fields being zeroed based on this
  later.
- Detect display presence already before the fused-off checks and only for
  HAS_DISPLAY().
v3: Fix "preset" vs "present" typo.
Reported-and-tested-by: iczero <iczero@hellomouse.net>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8015
Cc: iczero <iczero@hellomouse.net>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230208114300.3123934-4-imre.deak@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -116,6 +116,9 @@
  *  #define GEN8_BAR                    _MMIO(0xb888)
  */
 
+#define GU_CNTL_PROTECTED		_MMIO(0x10100C)
+#define   DEPRESENT			REG_BIT(9)
+
 #define GU_CNTL				_MMIO(0x101010)
 #define   LMEM_INIT			REG_BIT(7)
 #define   DRIVERFLR			REG_BIT(31)

drivers/gpu/drm/i915/intel_device_info.c

@@ -441,6 +441,14 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
 			runtime->num_sprites[pipe] = 1;
 	}
 
+	if (HAS_DISPLAY(dev_priv) &&
+	    (IS_DGFX(dev_priv) || DISPLAY_VER(dev_priv) >= 14) &&
+	    !(intel_de_read(dev_priv, GU_CNTL_PROTECTED) & DEPRESENT)) {
+		drm_info(&dev_priv->drm, "Display not present, disabling\n");
+
+		runtime->pipe_mask = 0;
+	}
+
 	if (HAS_DISPLAY(dev_priv) && IS_GRAPHICS_VER(dev_priv, 7, 8) &&
 	    HAS_PCH_SPLIT(dev_priv)) {
 		u32 fuse_strap = intel_de_read(dev_priv, FUSE_STRAP);