| Message ID | ZcfpqwnkSoiJxeT9@debian.local (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix divide-by-zero on DP unplug with nouveau | expand |
On Sat, Feb 10, 2024 at 09:24:59PM +0000, Chris Bainbridge wrote: Sorry for the delay. > The following trace occurs when using nouveau and unplugging a DP MST > adaptor: > > divide error: 0000 [#1] PREEMPT SMP PTI > CPU: 7 PID: 2962 Comm: Xorg Not tainted 6.8.0-rc3+ #744 > Hardware name: Razer Blade/DANA_MB, BIOS 01.01 08/31/2018 > RIP: 0010:drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > Code: c6 b8 01 00 00 00 75 61 01 c6 41 0f af f3 41 0f af f1 c1 e1 04 48 63 c7 31 d2 89 ff 48 8b 5d f8 c9 48 0f af f1 48 8d 44 06 ff <48> f7 f7 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 45 31 d2 45 31 > RSP: 0018:ffffb2c5c211fa30 EFLAGS: 00010206 > RAX: ffffffffffffffff RBX: 0000000000000000 RCX: 0000000000f59b00 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: ffffb2c5c211fa48 R08: 0000000000000001 R09: 0000000000000020 > R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000023b4a > R13: ffff91d37d165800 R14: ffff91d36fac6d80 R15: ffff91d34a764010 > FS: 00007f4a1ca3fa80(0000) GS:ffff91d6edbc0000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000559491d49000 CR3: 000000011d180002 CR4: 00000000003706f0 > Call Trace: > <TASK> > ? show_regs+0x6d/0x80 > ? die+0x37/0xa0 > ? do_trap+0xd4/0xf0 > ? do_error_trap+0x71/0xb0 > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > ? exc_divide_error+0x3a/0x70 > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > ? asm_exc_divide_error+0x1b/0x20 > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > ? drm_dp_calc_pbn_mode+0x2e/0x70 [drm_display_helper] > nv50_msto_atomic_check+0xda/0x120 [nouveau] > drm_atomic_helper_check_modeset+0xa87/0xdf0 [drm_kms_helper] > drm_atomic_helper_check+0x19/0xa0 [drm_kms_helper] > nv50_disp_atomic_check+0x13f/0x2f0 [nouveau] > drm_atomic_check_only+0x668/0xb20 [drm] > ? drm_connector_list_iter_next+0x86/0xc0 [drm] > drm_atomic_commit+0x58/0xd0 [drm] > ? __pfx___drm_printfn_info+0x10/0x10 [drm] > drm_atomic_connector_commit_dpms+0xd7/0x100 [drm] > drm_mode_obj_set_property_ioctl+0x1c5/0x450 [drm] > ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] > drm_connector_property_set_ioctl+0x3b/0x60 [drm] > drm_ioctl_kernel+0xb9/0x120 [drm] > drm_ioctl+0x2d0/0x550 [drm] > ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] > nouveau_drm_ioctl+0x61/0xc0 [nouveau] > __x64_sys_ioctl+0xa0/0xf0 > do_syscall_64+0x76/0x140 > ? do_syscall_64+0x85/0x140 > ? do_syscall_64+0x85/0x140 > entry_SYSCALL_64_after_hwframe+0x6e/0x76 > RIP: 0033:0x7f4a1cd1a94f > Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 77 1f 48 8b 44 24 18 64 48 2b 04 25 28 00 > RSP: 002b:00007ffd2f1df520 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00007ffd2f1df5b0 RCX: 00007f4a1cd1a94f > RDX: 00007ffd2f1df5b0 RSI: 00000000c01064ab RDI: 000000000000000f > RBP: 00000000c01064ab R08: 000056347932deb8 R09: 000056347a7d99c0 > R10: 0000000000000000 R11: 0000000000000246 R12: 000056347938a220 > R13: 000000000000000f R14: 0000563479d9f3f0 R15: 0000000000000000 > </TASK> > Modules linked in: rfcomm xt_conntrack nft_chain_nat xt_MASQUERADE nf_nat nf_conntrack_netlink nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xfrm_user xfrm_algo xt_addrtype nft_compat nf_tables nfnetlink br_netfilter bridge stp llc ccm cmac algif_hash overlay algif_skcipher af_alg bnep binfmt_misc snd_sof_pci_intel_cnl snd_sof_intel_hda_common snd_soc_hdac_hda snd_sof_pci snd_sof_xtensa_dsp snd_sof_intel_hda snd_sof snd_sof_utils snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core snd_compress snd_sof_intel_hda_mlink snd_hda_ext_core iwlmvm intel_rapl_msr intel_rapl_common intel_tcc_cooling x86_pkg_temp_thermal intel_powerclamp mac80211 coretemp kvm_intel snd_hda_codec_hdmi kvm snd_hda_codec_realtek snd_hda_codec_generic uvcvideo libarc4 snd_hda_intel snd_intel_dspcfg snd_hda_codec iwlwifi videobuf2_vmalloc videobuf2_memops uvc irqbypass btusb videobuf2_v4l2 snd_seq_midi crct10dif_pclmul hid_multitouch crc32_pclmul snd_seq_midi_event btrtl snd_hwdep videodev polyval_clmulni polyval_generic snd_rawmidi > ghash_clmulni_intel aesni_intel btintel crypto_simd snd_hda_core cryptd snd_seq btbcm ee1004 8250_dw videobuf2_common btmtk rapl nls_iso8859_1 mei_hdcp thunderbolt bluetooth intel_cstate wmi_bmof intel_wmi_thunderbolt cfg80211 snd_pcm mc snd_seq_device i2c_i801 r8169 ecdh_generic snd_timer i2c_smbus ecc snd mei_me intel_lpss_pci mei ahci intel_lpss soundcore realtek libahci idma64 intel_pch_thermal i2c_hid_acpi i2c_hid acpi_pad sch_fq_codel msr parport_pc ppdev lp parport efi_pstore ip_tables x_tables autofs4 dm_crypt raid10 raid456 libcrc32c async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq raid1 raid0 joydev input_leds hid_generic usbhid hid nouveau i915 drm_ttm_helper gpu_sched drm_gpuvm drm_exec i2c_algo_bit drm_buddy ttm drm_display_helper drm_kms_helper cec rc_core drm nvme nvme_core mxm_wmi xhci_pci xhci_pci_renesas video wmi pinctrl_cannonlake mac_hid > ---[ end trace 0000000000000000 ]--- > > Fix this by avoiding the divide if bpp is 0. > > Fixes: c1d6a22b7219 ("drm/dp: Add helpers to calculate the link BW overhead") > Signed-off-by: Chris Bainbridge <chris.bainbridge@gmail.com> > --- > drivers/gpu/drm/display/drm_dp_helper.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c > index b1ca3a1100da..bb8794c8f99c 100644 > --- a/drivers/gpu/drm/display/drm_dp_helper.c > +++ b/drivers/gpu/drm/display/drm_dp_helper.c > @@ -4024,6 +4024,9 @@ int drm_dp_bw_overhead(int lane_count, int hactive, > bpp_x16, symbol_size, > is_mst); > > + /* Avoid potential divide by zero in DIV_ROUND_UP_ULL */ The above comment is redundant. > + if (bpp_x16 == 0) > + return 0; Could you please move the check to the beginnig of the function and add a debug message in case bpp_x16 is 0? It looks odd that a driver calls this function with a 0 bpp_x16, and ideally it should be fixed in the driver. However as it's a regression and we don't have a better idea now: Acked-by: Imre Deak <imre.deak@intel.com> > return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * symbol_size * lane_count, > overhead * 16), > hactive * bpp_x16); > -- > 2.39.2 >
On 11.03.24 17:09, Imre Deak wrote: > On Sat, Feb 10, 2024 at 09:24:59PM +0000, Chris Bainbridge wrote: > Sorry for the delay. Happens, thx for looking onto this! >> The following trace occurs when using nouveau and unplugging a DP MST >> adaptor: > [...] >> + if (bpp_x16 == 0) >> + return 0; > > Could you please move the check to the beginnig of the function and add > a debug message in case bpp_x16 is 0? > > It looks odd that a driver calls this function with a 0 bpp_x16, and > ideally it should be fixed in the driver. However as it's a regression > and we don't have a better idea now: > > Acked-by: Imre Deak <imre.deak@intel.com> Chris: as this went into 6.8, please consider adding a stable-tag to ensure Greg picks this up. Ciao, Thorsten
On Mon, Mar 11, 2024 at 06:09:29PM +0200, Imre Deak wrote: > On Sat, Feb 10, 2024 at 09:24:59PM +0000, Chris Bainbridge wrote: > > Sorry for the delay. > > > The following trace occurs when using nouveau and unplugging a DP MST > > adaptor: > > > > divide error: 0000 [#1] PREEMPT SMP PTI > > CPU: 7 PID: 2962 Comm: Xorg Not tainted 6.8.0-rc3+ #744 > > Hardware name: Razer Blade/DANA_MB, BIOS 01.01 08/31/2018 > > RIP: 0010:drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > > Code: c6 b8 01 00 00 00 75 61 01 c6 41 0f af f3 41 0f af f1 c1 e1 04 48 63 c7 31 d2 89 ff 48 8b 5d f8 c9 48 0f af f1 48 8d 44 06 ff <48> f7 f7 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 45 31 d2 45 31 > > RSP: 0018:ffffb2c5c211fa30 EFLAGS: 00010206 > > RAX: ffffffffffffffff RBX: 0000000000000000 RCX: 0000000000f59b00 > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > > RBP: ffffb2c5c211fa48 R08: 0000000000000001 R09: 0000000000000020 > > R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000023b4a > > R13: ffff91d37d165800 R14: ffff91d36fac6d80 R15: ffff91d34a764010 > > FS: 00007f4a1ca3fa80(0000) GS:ffff91d6edbc0000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000559491d49000 CR3: 000000011d180002 CR4: 00000000003706f0 > > Call Trace: > > <TASK> > > ? show_regs+0x6d/0x80 > > ? die+0x37/0xa0 > > ? do_trap+0xd4/0xf0 > > ? do_error_trap+0x71/0xb0 > > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > > ? exc_divide_error+0x3a/0x70 > > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > > ? asm_exc_divide_error+0x1b/0x20 > > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > > ? drm_dp_calc_pbn_mode+0x2e/0x70 [drm_display_helper] > > nv50_msto_atomic_check+0xda/0x120 [nouveau] > > drm_atomic_helper_check_modeset+0xa87/0xdf0 [drm_kms_helper] > > drm_atomic_helper_check+0x19/0xa0 [drm_kms_helper] > > nv50_disp_atomic_check+0x13f/0x2f0 [nouveau] > > drm_atomic_check_only+0x668/0xb20 [drm] > > ? drm_connector_list_iter_next+0x86/0xc0 [drm] > > drm_atomic_commit+0x58/0xd0 [drm] > > ? __pfx___drm_printfn_info+0x10/0x10 [drm] > > drm_atomic_connector_commit_dpms+0xd7/0x100 [drm] > > drm_mode_obj_set_property_ioctl+0x1c5/0x450 [drm] > > ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] > > drm_connector_property_set_ioctl+0x3b/0x60 [drm] > > drm_ioctl_kernel+0xb9/0x120 [drm] > > drm_ioctl+0x2d0/0x550 [drm] > > ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] > > nouveau_drm_ioctl+0x61/0xc0 [nouveau] > > __x64_sys_ioctl+0xa0/0xf0 > > do_syscall_64+0x76/0x140 > > ? do_syscall_64+0x85/0x140 > > ? do_syscall_64+0x85/0x140 > > entry_SYSCALL_64_after_hwframe+0x6e/0x76 > > RIP: 0033:0x7f4a1cd1a94f > > Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 77 1f 48 8b 44 24 18 64 48 2b 04 25 28 00 > > RSP: 002b:00007ffd2f1df520 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > > RAX: ffffffffffffffda RBX: 00007ffd2f1df5b0 RCX: 00007f4a1cd1a94f > > RDX: 00007ffd2f1df5b0 RSI: 00000000c01064ab RDI: 000000000000000f > > RBP: 00000000c01064ab R08: 000056347932deb8 R09: 000056347a7d99c0 > > R10: 0000000000000000 R11: 0000000000000246 R12: 000056347938a220 > > R13: 000000000000000f R14: 0000563479d9f3f0 R15: 0000000000000000 > > </TASK> > > Modules linked in: rfcomm xt_conntrack nft_chain_nat xt_MASQUERADE nf_nat nf_conntrack_netlink nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xfrm_user xfrm_algo xt_addrtype nft_compat nf_tables nfnetlink br_netfilter bridge stp llc ccm cmac algif_hash overlay algif_skcipher af_alg bnep binfmt_misc snd_sof_pci_intel_cnl snd_sof_intel_hda_common snd_soc_hdac_hda snd_sof_pci snd_sof_xtensa_dsp snd_sof_intel_hda snd_sof snd_sof_utils snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core snd_compress snd_sof_intel_hda_mlink snd_hda_ext_core iwlmvm intel_rapl_msr intel_rapl_common intel_tcc_cooling x86_pkg_temp_thermal intel_powerclamp mac80211 coretemp kvm_intel snd_hda_codec_hdmi kvm snd_hda_codec_realtek snd_hda_codec_generic uvcvideo libarc4 snd_hda_intel snd_intel_dspcfg snd_hda_codec iwlwifi videobuf2_vmalloc videobuf2_memops uvc irqbypass btusb videobuf2_v4l2 snd_seq_midi crct10dif_pclmul hid_multitouch crc32_pclmul snd_seq_midi_event btrtl snd_hwdep videodev polyval_clmulni polyval_generic snd_rawmidi > > ghash_clmulni_intel aesni_intel btintel crypto_simd snd_hda_core cryptd snd_seq btbcm ee1004 8250_dw videobuf2_common btmtk rapl nls_iso8859_1 mei_hdcp thunderbolt bluetooth intel_cstate wmi_bmof intel_wmi_thunderbolt cfg80211 snd_pcm mc snd_seq_device i2c_i801 r8169 ecdh_generic snd_timer i2c_smbus ecc snd mei_me intel_lpss_pci mei ahci intel_lpss soundcore realtek libahci idma64 intel_pch_thermal i2c_hid_acpi i2c_hid acpi_pad sch_fq_codel msr parport_pc ppdev lp parport efi_pstore ip_tables x_tables autofs4 dm_crypt raid10 raid456 libcrc32c async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq raid1 raid0 joydev input_leds hid_generic usbhid hid nouveau i915 drm_ttm_helper gpu_sched drm_gpuvm drm_exec i2c_algo_bit drm_buddy ttm drm_display_helper drm_kms_helper cec rc_core drm nvme nvme_core mxm_wmi xhci_pci xhci_pci_renesas video wmi pinctrl_cannonlake mac_hid > > ---[ end trace 0000000000000000 ]--- > > > > Fix this by avoiding the divide if bpp is 0. > > > > Fixes: c1d6a22b7219 ("drm/dp: Add helpers to calculate the link BW overhead") > > Signed-off-by: Chris Bainbridge <chris.bainbridge@gmail.com> > > --- > > drivers/gpu/drm/display/drm_dp_helper.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c > > index b1ca3a1100da..bb8794c8f99c 100644 > > --- a/drivers/gpu/drm/display/drm_dp_helper.c > > +++ b/drivers/gpu/drm/display/drm_dp_helper.c > > @@ -4024,6 +4024,9 @@ int drm_dp_bw_overhead(int lane_count, int hactive, > > bpp_x16, symbol_size, > > is_mst); > > > > + /* Avoid potential divide by zero in DIV_ROUND_UP_ULL */ > > The above comment is redundant. > > > + if (bpp_x16 == 0) > > + return 0; > > Could you please move the check to the beginnig of the function and add > a debug message in case bpp_x16 is 0? Also for consistency could you also check if lane_count or hactive is 0, as this would also a lead to a div-by-zero error. > It looks odd that a driver calls this function with a 0 bpp_x16, and > ideally it should be fixed in the driver. However as it's a regression > and we don't have a better idea now: > > Acked-by: Imre Deak <imre.deak@intel.com> > > > return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * symbol_size * lane_count, > > overhead * 16), > > hactive * bpp_x16); > > -- > > 2.39.2 > >
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index b1ca3a1100da..bb8794c8f99c 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -4024,6 +4024,9 @@ int drm_dp_bw_overhead(int lane_count, int hactive, bpp_x16, symbol_size, is_mst); + /* Avoid potential divide by zero in DIV_ROUND_UP_ULL */ + if (bpp_x16 == 0) + return 0; return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * symbol_size * lane_count, overhead * 16), hactive * bpp_x16);
The following trace occurs when using nouveau and unplugging a DP MST adaptor: divide error: 0000 [#1] PREEMPT SMP PTI CPU: 7 PID: 2962 Comm: Xorg Not tainted 6.8.0-rc3+ #744 Hardware name: Razer Blade/DANA_MB, BIOS 01.01 08/31/2018 RIP: 0010:drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] Code: c6 b8 01 00 00 00 75 61 01 c6 41 0f af f3 41 0f af f1 c1 e1 04 48 63 c7 31 d2 89 ff 48 8b 5d f8 c9 48 0f af f1 48 8d 44 06 ff <48> f7 f7 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 45 31 d2 45 31 RSP: 0018:ffffb2c5c211fa30 EFLAGS: 00010206 RAX: ffffffffffffffff RBX: 0000000000000000 RCX: 0000000000f59b00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffb2c5c211fa48 R08: 0000000000000001 R09: 0000000000000020 R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000023b4a R13: ffff91d37d165800 R14: ffff91d36fac6d80 R15: ffff91d34a764010 FS: 00007f4a1ca3fa80(0000) GS:ffff91d6edbc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000559491d49000 CR3: 000000011d180002 CR4: 00000000003706f0 Call Trace: <TASK> ? show_regs+0x6d/0x80 ? die+0x37/0xa0 ? do_trap+0xd4/0xf0 ? do_error_trap+0x71/0xb0 ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] ? exc_divide_error+0x3a/0x70 ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] ? asm_exc_divide_error+0x1b/0x20 ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] ? drm_dp_calc_pbn_mode+0x2e/0x70 [drm_display_helper] nv50_msto_atomic_check+0xda/0x120 [nouveau] drm_atomic_helper_check_modeset+0xa87/0xdf0 [drm_kms_helper] drm_atomic_helper_check+0x19/0xa0 [drm_kms_helper] nv50_disp_atomic_check+0x13f/0x2f0 [nouveau] drm_atomic_check_only+0x668/0xb20 [drm] ? drm_connector_list_iter_next+0x86/0xc0 [drm] drm_atomic_commit+0x58/0xd0 [drm] ? __pfx___drm_printfn_info+0x10/0x10 [drm] drm_atomic_connector_commit_dpms+0xd7/0x100 [drm] drm_mode_obj_set_property_ioctl+0x1c5/0x450 [drm] ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] drm_connector_property_set_ioctl+0x3b/0x60 [drm] drm_ioctl_kernel+0xb9/0x120 [drm] drm_ioctl+0x2d0/0x550 [drm] ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] nouveau_drm_ioctl+0x61/0xc0 [nouveau] __x64_sys_ioctl+0xa0/0xf0 do_syscall_64+0x76/0x140 ? do_syscall_64+0x85/0x140 ? do_syscall_64+0x85/0x140 entry_SYSCALL_64_after_hwframe+0x6e/0x76 RIP: 0033:0x7f4a1cd1a94f Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 77 1f 48 8b 44 24 18 64 48 2b 04 25 28 00 RSP: 002b:00007ffd2f1df520 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffd2f1df5b0 RCX: 00007f4a1cd1a94f RDX: 00007ffd2f1df5b0 RSI: 00000000c01064ab RDI: 000000000000000f RBP: 00000000c01064ab R08: 000056347932deb8 R09: 000056347a7d99c0 R10: 0000000000000000 R11: 0000000000000246 R12: 000056347938a220 R13: 000000000000000f R14: 0000563479d9f3f0 R15: 0000000000000000 </TASK> Modules linked in: rfcomm xt_conntrack nft_chain_nat xt_MASQUERADE nf_nat nf_conntrack_netlink nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xfrm_user xfrm_algo xt_addrtype nft_compat nf_tables nfnetlink br_netfilter bridge stp llc ccm cmac algif_hash overlay algif_skcipher af_alg bnep binfmt_misc snd_sof_pci_intel_cnl snd_sof_intel_hda_common snd_soc_hdac_hda snd_sof_pci snd_sof_xtensa_dsp snd_sof_intel_hda snd_sof snd_sof_utils snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core snd_compress snd_sof_intel_hda_mlink snd_hda_ext_core iwlmvm intel_rapl_msr intel_rapl_common intel_tcc_cooling x86_pkg_temp_thermal intel_powerclamp mac80211 coretemp kvm_intel snd_hda_codec_hdmi kvm snd_hda_codec_realtek snd_hda_codec_generic uvcvideo libarc4 snd_hda_intel snd_intel_dspcfg snd_hda_codec iwlwifi videobuf2_vmalloc videobuf2_memops uvc irqbypass btusb videobuf2_v4l2 snd_seq_midi crct10dif_pclmul hid_multitouch crc32_pclmul snd_seq_midi_event btrtl snd_hwdep videodev polyval_clmulni polyval_generic snd_rawmidi ghash_clmulni_intel aesni_intel btintel crypto_simd snd_hda_core cryptd snd_seq btbcm ee1004 8250_dw videobuf2_common btmtk rapl nls_iso8859_1 mei_hdcp thunderbolt bluetooth intel_cstate wmi_bmof intel_wmi_thunderbolt cfg80211 snd_pcm mc snd_seq_device i2c_i801 r8169 ecdh_generic snd_timer i2c_smbus ecc snd mei_me intel_lpss_pci mei ahci intel_lpss soundcore realtek libahci idma64 intel_pch_thermal i2c_hid_acpi i2c_hid acpi_pad sch_fq_codel msr parport_pc ppdev lp parport efi_pstore ip_tables x_tables autofs4 dm_crypt raid10 raid456 libcrc32c async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq raid1 raid0 joydev input_leds hid_generic usbhid hid nouveau i915 drm_ttm_helper gpu_sched drm_gpuvm drm_exec i2c_algo_bit drm_buddy ttm drm_display_helper drm_kms_helper cec rc_core drm nvme nvme_core mxm_wmi xhci_pci xhci_pci_renesas video wmi pinctrl_cannonlake mac_hid ---[ end trace 0000000000000000 ]--- Fix this by avoiding the divide if bpp is 0. Fixes: c1d6a22b7219 ("drm/dp: Add helpers to calculate the link BW overhead") Signed-off-by: Chris Bainbridge <chris.bainbridge@gmail.com> --- drivers/gpu/drm/display/drm_dp_helper.c | 3 +++ 1 file changed, 3 insertions(+)