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82c362f2c6
When the PHY fails on calibration we were previously skipping the ddi
initialization. However the driver is not really prepared for that,
ultimately leading to a NULL pointer dereference:
[ 75.748348] i915 0000:03:00.0: [drm:intel_modeset_init_nogem [i915]] SNPS PHY A failed to calibrate; output will not be used.
...
[ 75.750336] i915 0000:03:00.0: [drm:intel_modeset_setup_hw_state [i915]] [CRTC:80:pipe A] hw state readout: enabled
...
( no DDI A/PHY A )
[ 75.753080] i915 0000:03:00.0: [drm:intel_modeset_setup_hw_state [i915]] [ENCODER:235:DDI B/PHY B] hw state readout: disabled, pipe A
[ 75.753164] i915 0000:03:00.0: [drm:intel_modeset_setup_hw_state [i915]] [ENCODER:245:DDI C/PHY C] hw state readout: disabled, pipe A
...
[ 75.754425] i915 0000:03:00.0: [drm] *ERROR* crtc 80: Can't calculate constants, dotclock = 0!
[ 75.765558] i915 0000:03:00.0: drm_WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev))
[ 75.765569] WARNING: CPU: 5 PID: 1759 at drivers/gpu/drm/drm_vblank.c:728 drm_crtc_vblank_helper_get_vblank_timestamp_internal+0x347/0x360
...
[ 75.781230] BUG: kernel NULL pointer dereference, address: 000000000000007c
[ 75.788198] #PF: supervisor read access in kernel mode
[ 75.793347] #PF: error_code(0x0000) - not-present page
[ 75.798480] PGD 0 P4D 0
[ 75.801019] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 75.805377] CPU: 5 PID: 1759 Comm: modprobe Tainted: G W 5.18.0-rc1-demarchi+ #199
[ 75.827613] RIP: 0010:icl_aux_power_well_disable+0x3b/0x200 [i915]
[ 75.833890] Code: 83 ec 30 65 48 8b 04 25 28 00 00 00 48 89 44 24 28 48 8b 06 0f b6 70 1c f6 40 20 04 8d 56 fa 0f 45 f2 e8 88 bd ff ff 48 89 ef <8b> 70 7c e8 ed 67 ff ff 48 89 ef 89 c6 e8 73 67 ff ff 84 c0 75 0a
[ 75.852629] RSP: 0018:ffffc90003a7fb30 EFLAGS: 00010246
[ 75.857852] RAX: 0000000000000000 RBX: ffff8881145e8f10 RCX: 0000000000000000
[ 75.864978] RDX: ffff888115220840 RSI: 0000000000000000 RDI: ffff888115220000
[ 75.872106] RBP: ffff888115220000 R08: ffff88888effffe8 R09: 00000000fffdffff
[ 75.879234] R10: ffff88888e200000 R11: ffff88888ed00000 R12: ffff8881145e8f10
[ 75.886363] R13: 0000000000000001 R14: ffff888115223240 R15: 0000000000000000
[ 75.893490] FS: 00007ff6e753a740(0000) GS:ffff88888f680000(0000) knlGS:0000000000000000
[ 75.901573] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 75.907313] CR2: 000000000000007c CR3: 00000001216a6001 CR4: 0000000000770ee0
[ 75.914446] PKRU: 55555554
[ 75.917153] Call Trace:
[ 75.919603] <TASK>
[ 75.921709] intel_power_domains_sanitize_state+0x88/0xb0 [i915]
[ 75.927814] intel_modeset_init_nogem+0x317/0xef0 [i915]
[ 75.933205] i915_driver_probe+0x5f6/0xdf0 [i915]
[ 75.937976] i915_pci_probe+0x51/0x1d0 [i915]
We skip the initialization of PHY A, but later we try to find out what
is the phy for that power well and dereference dig_port, which is NULL.
Failing the PHY calibration could be left as a warning or error, like it
was before commit
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.