Warning for driver i915 for 4.17.0-rcX

[Larry Finger]

With kernel 4.17.0-rc3, I noted the following warning from driver i915.

kernel: ------------[ cut here ]------------
kernel: Could not determine valid watermarks for inherited state
kernel: WARNING: CPU: 3 PID: 224 at drivers/gpu/drm/i915/intel_display.c:14584 
intel_modeset_init+0x3be/0x1060 [i915]
kernel: Modules linked in: i915(+) xhci_pci i2c_algo_bit ehci_pci xhci_hcd 
serio_raw drm_kms_helper ehci_hcd syscopyarea sysfillrect sysimgblt
kernel: CPU: 3 PID: 224 Comm: systemd-udevd Not tainted 
4.17.0-rc0-08000-g2f39cfca0161-dirty #188
kernel: Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS Version 4.50 
09/29/2014
kernel: RIP: 0010:intel_modeset_init+0x3be/0x1060 [i915]
kernel: RSP: 0018:ffffc9000112fab8 EFLAGS: 00010296
kernel: RAX: 0000000000000038 RBX: ffff88021dc10000 RCX: 0000000000000006
kernel: RDX: 0000000000000007 RSI: 0000000000000082 RDI: ffff88022f2d5bd0
kernel: RBP: ffff88021c8b3000 R08: 0000000000000289 R09: 0000000000000004
kernel: R10: ffffc9000112f948 R11: 0000000000000001 R12: ffff88021ef3d800
kernel: R13: 00000000ffffffea R14: 0000000000000000 R15: ffff88021dc10358
kernel: FS:  00007f830913c940(0000) GS:ffff88022f2c0000(0000) knlGS:0000000000000000
kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kernel: CR2: 00007ffc91722f58 CR3: 000000021e940003 CR4: 00000000001606e0
kernel: Call Trace:
kernel:  i915_driver_load+0xa87/0xed0 [i915]
kernel:  local_pci_probe+0x42/0xa0
kernel:  pci_device_probe+0x125/0x190
kernel:  driver_probe_device+0x30b/0x480
kernel:  __driver_attach+0xb8/0xe0
kernel:  ? driver_probe_device+0x40/0x480
kernel:  ? driver_probe_device+0x480/0x480
kernel:  bus_for_each_dev+0x65/0x90
kernel:  bus_add_driver+0x161/0x260
kernel:  ? 0xffffffffa0149000
kernel:  driver_register+0x57/0xc0
kernel:  ? 0xffffffffa0149000
kernel:  do_one_initcall+0x4e/0x18d
kernel:  ? kmem_cache_alloc_trace+0xfe/0x210
kernel:  ? do_init_module+0x22/0x20a
kernel:  do_init_module+0x5b/0x20a
kernel:  load_module+0x18a1/0x1e20
kernel:  ? SYSC_finit_module+0xb7/0xd0
kernel:  SYSC_finit_module+0xb7/0xd0
kernel:  do_syscall_64+0x6e/0x120
kernel:  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
kernel: RIP: 0033:0x7f8307f67529
kernel: RSP: 002b:00007ffc91737ab8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
kernel: RAX: ffffffffffffffda RBX: 0000559b3cf6f350 RCX: 00007f8307f67529
kernel: RDX: 0000000000000000 RSI: 00007f83088cd83d RDI: 0000000000000014
kernel: RBP: 00007f83088cd83d R08: 0000000000000000 R09: 0000559b3cf44f50
kernel: R10: 0000000000000014 R11: 0000000000000246 R12: 0000000000020000
kernel: R13: 0000559b3cf634a0 R14: 0000000000000000 R15: 0000000003938700
kernel: Code: 00 f7 c6 00 00 18 00 0f 84 d7 0a 00 00 85 c9 0f 94 c1 41 88 8c 24 
8d 02 00 00 e9 f6 08 00 00 48 c7 c7 b0 2f 41 a0 e8 f2 9b cd e0
kernel: ---[ end trace c0feea6402f4c999 ]---

This warning was bisected to

commit a2936e3d9a9cb2ce192455cdec3a8cfccc26b486 (refs/bisect/bad)
Author: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>
Date:   Thu Nov 23 21:04:49 2017 +0200

    drm/i915: Use drm_mode_get_hv_timing() to populate plane clip rectangle

    Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
    Signed-off-by: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>
    Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
    Reviewed-by: Thierry Reding <treding@xxxxxxxxxx>

The output of 'lspci -nn -vvv' for the gracpics device is as follows:

00:02.0 VGA compatible controller [0300]: Intel Corporation 4th Gen Core 
Processor Integrated Graphics Controller [8086:0416] (rev 06) (prog-if 00 [VGA 
controller])
        Subsystem: Toshiba America Info Systems Device [1179:0002]
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- 
<MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Interrupt: pin A routed to IRQ 28
        Region 0: Memory at e0000000 (64-bit, non-prefetchable) [size=4M]
        Region 2: Memory at d0000000 (64-bit, prefetchable) [size=256M]
        Region 4: I/O ports at 4000 [size=64]
        [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
        Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
                Address: fee00018  Data: 0000
        Capabilities: [d0] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [a4] PCI Advanced Features
                AFCap: TP+ FLR+
                AFCtrl: FLR-
                AFStatus: TP-
        Kernel driver in use: i915
        Kernel modules: i915

This warning does not seem to cause any problems.

Thanks,

Larry