Message-ID: <aPUtb50BDUOgSg8N@ideak-desk>
Date: Sun, 19 Oct 2025 21:26:55 +0300
From: Imre Deak <imre.deak@...el.com>
To: ALOK TIWARI <alok.a.tiwari@...cle.com>
CC: <dri-devel@...ts.freedesktop.org>, <intel-xe@...ts.freedesktop.org>,
	<intel-gfx@...ts.freedesktop.org>, Simona Vetter <simona@...ll.ch>, "David
 Airlie" <airlied@...il.com>, <tursulin@...ulin.net>,
	<joonas.lahtinen@...ux.intel.com>, <rodrigo.vivi@...el.com>,
	<jani.nikula@...ux.intel.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, <alok.a.tiwarilinux@...il.com>, Ville
 Syrjälä <ville.syrjala@...ux.intel.com>
Subject: Re: [bug-report] i915 DMC assert crash on HDMI hotplug

On Sun, Oct 19, 2025 at 07:51:08PM +0530, ALOK TIWARI wrote:
> Hi,
> 
> On a Lenovo 12TECTO1WW HW (BIOS M5HKT1DA), the i915 DRM driver triggers a
> DMC firmware assertion
> when connecting or disconnecting an HDMI display. The GPU firmware (DMC)
> registers show incorrect
> values, causing assert_dmc_loaded() to warn in intel_dmc.c.
> 
> This occurs on kernel 6.18-rc1 and appears related to DMC power and hotplug
> handling.
> 
> Kernel: 6.18.0-rc1

This looks like
https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15153

Could you attach a dmesg log to the above ticket booting with the
drm.debug=0xe kernel parameter and reproducing the problem?

> 
> ---
> 
> [  130.665424] audit: type=1326 audit(1760882657.655:78): auid=1001 uid=1001
> gid=1001 ses=3 subj=snap.snapd-desktop-integration.snapd-desktop-integration
> pid=2408 comm="snapd-desktop-i"
> exe="/snap/snapd-desktop-integration/315/usr/bin/snapd-desktop-integration"
> sig=0 arch=c000003e syscall=203 compat=0 ip=0x7e4ba6bc4531 code=0x50000
> [  131.287051] nvme nvme0: using unchecked data buffer
> intel_dmcintel_dmc[  218.492264] ------------[ cut here ]------------
> [  218.492268] i915 0000:00:02.0: [drm] DMC 0 mmio[5]/0x8f03c incorrect
> (expected 0x30100, current 0x0)
> [  218.492292] WARNING: CPU: 6 PID: 409 at
> drivers/gpu/drm/i915/display/intel_dmc.c:645 assert_dmc_loaded+0x2c1/0x420
> [i915]
> [  218.492455] Modules linked in: rfcomm ccm cmac algif_hash algif_skcipher
> af_alg xe snd_hda_codec_intelhdmi drm_gpuvm drm_gpusvm_helper
> snd_hda_codec_alc269 gpu_sched snd_hda_scodec_component drm_ttm_helper
> snd_hda_codec_realtek_lib drm_exec snd_hda_codec_generic drm_suballoc_helper
> intel_uncore_frequency intel_uncore_frequency_common i915 snd_hda_intel
> snd_sof_pci_intel_tgl snd_sof_pci_intel_cnl snd_sof_intel_hda_generic
> soundwire_intel snd_sof_intel_hda_sdw_bpt snd_sof_intel_hda_common
> snd_soc_hdac_hda snd_sof_intel_hda_mlink snd_sof_intel_hda
> snd_hda_codec_hdmi soundwire_cadence snd_sof_pci snd_sof_xtensa_dsp snd_sof
> iwlmvm snd_sof_utils snd_soc_acpi_intel_match bnep
> snd_soc_acpi_intel_sdca_quirks soundwire_generic_allocation snd_soc_acpi
> soundwire_bus x86_pkg_temp_thermal snd_soc_sdca intel_powerclamp mac80211
> crc8 snd_soc_avs snd_soc_hda_codec snd_hda_ext_core snd_hda_codec coretemp
> kvm_intel snd_hda_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hwdep
> snd_soc_core kvm libarc4 snd_compress iwlwifi ac97_bus
> [  218.492496]  snd_pcm_dmaengine snd_pcm snd_seq_midi snd_seq_midi_event
> snd_rawmidi binfmt_misc snd_seq cmdlinepart processor_thermal_device_pci
> btusb processor_thermal_device spi_nor snd_seq_device btmtk
> processor_thermal_wt_hint drm_buddy platform_temperature_control snd_timer
> btrtl irqbypass ttm processor_thermal_soc_slider polyval_clmulni
> nls_iso8859_1 ghash_clmulni_intel platform_profile btbcm aesni_intel
> mei_hdcp think_lmi processor_thermal_rfim btintel mei_pxp rapl snd
> intel_rapl_msr processor_thermal_rapl cfg80211 bluetooth
> firmware_attributes_class input_leds drm_display_helper intel_cstate mtd
> mei_me joydev wmi_bmof intel_rapl_common soundcore cec ecdh_generic
> processor_thermal_wt_req ecc mei rc_core processor_thermal_power_floor
> intel_pmc_core i2c_algo_bit processor_thermal_mbox pmt_telemetry
> pmt_discovery pmt_class intel_pmc_ssram_telemetry int3400_thermal
> int3403_thermal intel_vsec acpi_thermal_rel int340x_thermal_zone acpi_pad
> acpi_tad mac_hid sch_fq_codel msr parport_pc ppdev lp parport efi_pstore
> [  218.492543]  autofs4 btrfs blake2b_generic raid10 raid456
> async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq
> raid1 raid0 hid_generic usbhid nvme i2c_i801 e1000e nvme_core hid i2c_mux
> nvme_keyring i2c_smbus ahci spi_intel_pci nvme_auth spi_intel libahci hkdf
> video wmi
> [  218.492563] CPU: 6 UID: 0 PID: 409 Comm: kworker/u32:8 Not tainted
> 6.18.0-rc1 #3 PREEMPT(voluntary)
> [  218.492566] Hardware name: LENOVO 12TECTO1WW/3355, BIOS M5HKT1DA
> 06/17/2025
> [  218.492568] Workqueue: events_unbound intel_display_power_put_async_work
> [i915]
> [  218.492706] RIP: 0010:assert_dmc_loaded+0x2c1/0x420 [i915]
> [  218.492840] Code: 55 a8 e8 52 2d 9c cf 44 8b 45 cc 8b 4d bc 45 89 e9 48
> 89 c6 8b 45 c8 48 8b 55 a8 48 c7 c7 28 7e db c1 50 41 56 e8 9f 19 e4 ce <0f>
> 0b 58 5a e9 92 fe ff ff 48 8b 17 eb c6 48 8b 3b 48 85 ff 74 04
> [  218.492842] RSP: 0018:ffffd04682ff7c48 EFLAGS: 00010246
> [  218.492844] RAX: 0000000000000000 RBX: ffff8ef885a22000 RCX:
> 0000000000000000
> [  218.492845] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> 0000000000000000
> [  218.492846] RBP: ffffd04682ff7cb0 R08: 0000000000000000 R09:
> 0000000000000000
> [  218.492847] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [  218.492848] R13: 000000000008f03c R14: 0000000000030100 R15:
> 0000000000000005
> [  218.492850] FS:  0000000000000000(0000) GS:ffff8efc32794000(0000)
> knlGS:0000000000000000
> [  218.492851] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  218.492852] CR2: 000075deec01b098 CR3: 00000001fba40006 CR4:
> 0000000000f72ef0
> [  218.492854] PKRU: 55555554
> [  218.492855] Call Trace:
> [  218.492856]  <TASK>
> [  218.492860]  assert_main_dmc_loaded+0x10/0x20 [i915]
> [  218.492990]  skl_enable_dc6+0xad/0x230 [i915]
> [  218.493113]  gen9_dc_off_power_well_disable+0xb8/0xd0 [i915]
> [  218.493244]  intel_power_well_disable+0x67/0x80 [i915]
> [  218.493394]  intel_power_well_put+0x4b/0xc0 [i915]
> [  218.493523]  __intel_display_power_put_domain+0xc7/0x1d0 [i915]
> [  218.493649]  release_async_put_domains+0x5b/0x90 [i915]
> [  218.493774]  intel_display_power_put_async_work+0x6b/0x170 [i915]
> [  218.493896]  process_one_work+0x1a1/0x3f0
> [  218.493901]  worker_thread+0x2ba/0x3d0
> [  218.493904]  kthread+0x107/0x220
> [  218.493906]  ? __pfx_worker_thread+0x10/0x10
> [  218.493908]  ? __pfx_kthread+0x10/0x10
> [  218.493910]  ret_from_fork+0x202/0x230
> [  218.493912]  ? __pfx_kthread+0x10/0x10
> [  218.493914]  ret_from_fork_asm+0x1a/0x30
> [  218.493918]  </TASK>
> [  218.493919] ---[ end trace 0000000000000000 ]---
> [  218.493921] ------------[ cut here ]------------
> [  218.493921] i915 0000:00:02.0: [drm] DMC 0 mmio[6]/0x8f00c incorrect
> (expected 0x40b8408c, current 0x0)
> [  218.493937] WARNING: CPU: 6 PID: 409 at
> drivers/gpu/drm/i915/display/intel_dmc.c:645 assert_dmc_loaded+0x2c1/0x420
> [i915]
> [  218.494063] Modules linked in: rfcomm ccm cmac algif_hash algif_skcipher
> af_alg xe snd_hda_codec_intelhdmi drm_gpuvm drm_gpusvm_helper
> snd_hda_codec_alc269 gpu_sched snd_hda_scodec_component drm_ttm_helper
> snd_hda_codec_realtek_lib drm_exec snd_hda_codec_generic drm_suballoc_helper
> intel_uncore_frequency intel_uncore_frequency_common i915 snd_hda_intel
> snd_sof_pci_intel_tgl snd_sof_pci_intel_cnl snd_sof_intel_hda_generic
> soundwire_intel snd_sof_intel_hda_sdw_bpt snd_sof_intel_hda_common
> snd_soc_hdac_hda snd_sof_intel_hda_mlink snd_sof_intel_hda
> snd_hda_codec_hdmi soundwire_cadence snd_sof_pci snd_sof_xtensa_dsp snd_sof
> iwlmvm snd_sof_utils snd_soc_acpi_intel_match bnep
> snd_soc_acpi_intel_sdca_quirks soundwire_generic_allocation snd_soc_acpi
> soundwire_bus x86_pkg_temp_thermal snd_soc_sdca intel_powerclamp mac80211
> crc8 snd_soc_avs snd_soc_hda_codec snd_hda_ext_core snd_hda_codec coretemp
> kvm_intel snd_hda_core snd_intel_dspcfg snd_intel_sdw_acpi snd_hwdep
> snd_soc_core kvm libarc4 snd_compress iwlwifi ac97_bus
> [  218.494101]  snd_pcm_dmaengine snd_pcm snd_seq_midi snd_seq_midi_event
> snd_rawmidi binfmt_misc snd_seq cmdlinepart processor_thermal_device_pci
> btusb processor_thermal_device spi_nor snd_seq_device btmtk
> processor_thermal_wt_hint drm_buddy platform_temperature_control snd_timer
> btrtl irqbypass ttm processor_thermal_soc_slider polyval_clmulni
> nls_iso8859_1 ghash_clmulni_intel platform_profile btbcm aesni_intel
> mei_hdcp think_lmi processor_thermal_rfim btintel mei_pxp rapl snd
> intel_rapl_msr processor_thermal_rapl cfg80211 bluetooth
> firmware_attributes_class input_leds drm_display_helper intel_cstate mtd
> mei_me joydev wmi_bmof intel_rapl_common soundcore cec ecdh_generic
> processor_thermal_wt_req ecc mei rc_core processor_thermal_power_floor
> intel_pmc_core i2c_algo_bit processor_thermal_mbox pmt_telemetry
> pmt_discovery pmt_class intel_pmc_ssram_telemetry int3400_thermal
> int3403_thermal intel_vsec acpi_thermal_rel int340x_thermal_zone acpi_pad
> acpi_tad mac_hid sch_fq_codel msr parport_pc ppdev lp parport efi_pstore
> [  218.494145]  autofs4 btrfs blake2b_generic raid10 raid456
> async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq
> raid1 raid0 hid_generic usbhid nvme i2c_i801 e1000e nvme_core hid i2c_mux
> nvme_keyring i2c_smbus ahci spi_intel_pci nvme_auth spi_intel libahci hkdf
> video wmi
> [  218.494165] CPU: 6 UID: 0 PID: 409 Comm: kworker/u32:8 Tainted: G    W
> 6.18.0-rc1 #3 PREEMPT(voluntary)
> [  218.494168] Tainted: [W]=WARN
> [  218.494169] Hardware name: LENOVO 12TECTO1WW/3355, BIOS M5HKT1DA
> 06/17/2025
> [  218.494170] Workqueue: events_unbound intel_display_power_put_async_work
> [i915]
> [  218.494309] RIP: 0010:assert_dmc_loaded+0x2c1/0x420 [i915]
> [  218.494435] Code: 55 a8 e8 52 2d 9c cf 44 8b 45 cc 8b 4d bc 45 89 e9 48
> 89 c6 8b 45 c8 48 8b 55 a8 48 c7 c7 28 7e db c1 50 41 56 e8 9f 19 e4 ce <0f>
> 0b 58 5a e9 92 fe ff ff 48 8b 17 eb c6 48 8b 3b 48 85 ff 74 04
> [  218.494437] RSP: 0018:ffffd04682ff7c48 EFLAGS: 00010246
> [  218.494439] RAX: 0000000000000000 RBX: ffff8ef885a22000 RCX:
> 0000000000000000
> [  218.494440] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> 0000000000000000
> [  218.494441] RBP: ffffd04682ff7cb0 R08: 0000000000000000 R09:
> 0000000000000000
> [  218.494442] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [  218.494443] R13: 000000000008f00c R14: 0000000040b8408c R15:
> 0000000000000006
> [  218.494444] FS:  0000000000000000(0000) GS:ffff8efc32794000(0000)
> knlGS:0000000000000000
> [  218.494446] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  218.494447] CR2: 000075deec01b098 CR3: 00000001fba40006 CR4:
> 0000000000f72ef0
> [  218.494448] PKRU: 55555554
> [  218.494449] Call Trace:
> [  218.494450]  <TASK>
> [  218.494452]  assert_main_dmc_loaded+0x10/0x20 [i915]
> [  218.494572]  skl_enable_dc6+0xad/0x230 [i915]
> [  218.494667]  gen9_dc_off_power_well_disable+0xb8/0xd0 [i915]
> [  218.494757]  intel_power_well_disable+0x67/0x80 [i915]
> [  218.494845]  intel_power_well_put+0x4b/0xc0 [i915]
> [  218.494930]  __intel_display_power_put_domain+0xc7/0x1d0 [i915]
> [  218.495015]  release_async_put_domains+0x5b/0x90 [i915]
> [  218.495099]  intel_display_power_put_async_work+0x6b/0x170 [i915]
> [  218.495181]  process_one_work+0x1a1/0x3f0
> [  218.495184]  worker_thread+0x2ba/0x3d0
> [  218.495185]  kthread+0x107/0x220
> [  218.495187]  ? __pfx_worker_thread+0x10/0x10
> [  218.495189]  ? __pfx_kthread+0x10/0x10
> [  218.495190]  ret_from_fork+0x202/0x230
> [  218.495191]  ? __pfx_kthread+0x10/0x10
> [  218.495192]  ret_from_fork_asm+0x1a/0x30
> [  218.495195]  </TASK>
> [  218.495195] ---[ end trace 0000000000000000 ]---
> 
> 
> Thanks,
> Alok

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