imgtec ci20 HDMI broken

imgtec ci20 HDMI broken

[Waldemar Brodkorb]

Hi,

I recently played a little bit with ci20 devices.
It seems HDMI is broken in Linux 7.1.6.

Here is the kernel oops captured via serial console:

[   54.997593] dw-hdmi-ingenic 10180000.hdmi: Detected HDMI \X controller v1.31a with HDCP (DWC HDMI 3D TX PHY)
[   55.491338] dw-hdmi-ingenic 10180000.hdmi: registered DesignWare HDMI I2C bus driver
[   55.899132] [drm] DRM bridge corrupted or not allocated by devm_drm_bridge_alloc()
[   55.904136] ------------[ cut here ]------------
[   55.908753] WARNING: lib/refcount.c:25 at drm_bridge_get+0x58/0x6c [drm], CPU#0: kworker/u4:2/36
[   55.917538] refcount_t: addition on 0; use-after-free.
[   55.922553] Modules linked in: ingenic_dw_hdmi ingenic_drm hci_uart dw_hdmi v4l2_fwnode drm_dma_helper drm_display_helper drm_client_lib display_connector btbcm b
rcmfmac_cyw brcmfmac_wcc brcmfmac_bca v4l2_async msi001 fc2580 e4000 drm_kms_helper brcmfmac bluetooth au8522_decoder xc5000 xc4000 xc2028 videodev tuner_simple tda1
0071 tda1004x tda10048 stv0299 sp887x sp2 si2165 si2157 rc_zx_irdec rc_xbox_dvd rc_xbox_360 rc_x96max rc_winfast_usbii_deluxe rc_winfast rc_wetek_play2 rc_wetek_hub 
rc_videostrong_kii_pro rc_videomate_tv_pvr rc_videomate_s350 rc_videomate_m1f rc_vega_s9x rc_twinhan1027 rc_twinhan_dtv_cab_ci rc_tt_1500 rc_trekstor rc_total_media_
in_hend_02 rc_total_media_in_hand rc_tivo rc_tevii_nec rc_terratec_slim_2 rc_terratec_slim rc_terratec_cinergy_xs rc_terratec_cinergy_s2_hd rc_terratec_cinergy_c_pci
 rc_technisat_usb2 rc_technisat_ts35 rc_tbs_nec rc_tanix_tx5max rc_tanix_tx3mini rc_su3000 rc_streamzap rc_snapstream_firefly rc_siemens_gigaset_rc20 rc_reddo rc_rea
l_audio_220_32_keys rc_rc6_mce rc_pv951
[   55.923042]  rc_purpletv rc_proteus_2309 rc_powercolor_real_angel rc_pixelview_new rc_pixelview_mk12 rc_pixelview_002t rc_pixelview rc_pinnacle_pctv_hd rc_pinnacle_grey rc_pinnacle_color rc_pine64 rc_pctv_sedna rc_odroid rc_npgtech rc_norwood rc_nec_terratec_cinergy_xs rc_nebula rc_mygica_utv3 rc_msi_tvanywhere_plus rc_msi_tvanywhere rc_msi_digivox_iii rc_msi_digivox_ii rc_minix_neo rc_medion_x10_or2x rc_medion_x10_digitainer rc_medion_x10 rc_mecool_kiii_pro rc_mecool_kii_pro rc_manli rc_lme2510 rc_leadtek_y04g0051 rc_kworld_plus_tv_analog rc_kworld_pc150u rc_kworld_315u rc_khamsin rc_khadas rc_kaiomy rc_it913x_v2 rc_it913x_v1 rc_iodata_bctv7e rc_imon_rsc rc_imon_pad rc_imon_mce rc_hisi_tv_demo rc_hisi_poplar rc_hauppauge rc_gotview7135 rc_genius_tvgo_a11mce rc_geekbox rc_gadmei_rm008z rc_fusionhdtv_mce rc_flyvideo rc_flydvb rc_eztv rc_evga_indtube rc_encore_enltv2 rc_encore_enltv_fm53 rc_encore_enltv rc_em_terratec rc_dvico_portable rc_dvico_mce rc_dvbsky rc_dtt200u rc_dreambox rc_dntv_live_dvbt_pro
[   56.012798]  rc_dntv_live_dvb_t rc_dm1105_nec rc_digittrade rc_digitalnow_tinytwin rc_dib0700_rc5 rc_dib0700_nec rc_delock_61959 rc_d680_dmb rc_ct_90405 rc_cinergy_1400 rc_cinergy rc_budget_ci_old rc_behold_columbus rc_behold rc_beelink_mxiii rc_beelink_gs1 rc_azurewave_ad_tu700 rc_avertv_303 rc_avermedia_rm_ks rc_avermedia_m733a_rm_k6 rc_avermedia_m135a rc_avermedia_dvbt rc_avermedia_cardbus rc_avermedia_a16d rc_avermedia rc_ati_x10 rc_ati_tv_wonder_hd_600 rc_asus_ps3_100 rc_asus_pc39 rc_astrometa_t2hybrid rc_apac_viewcomp rc_anysee rc_alink_dtu_m rc_adstech_dvb_t_pci or51211 or51132 nxt200x mxl692 mn88473 mn88472 lgs8gxx ir_kbd_i2c ingenic_rng gpio_ir_tx gpio_ir_recv ecdh_generic ds3000 drxk drxd drx39xyj drm dib9000 dib8000 dib7000p dib7000m dib3000mc cxd2880_spi cx24120 cx24117 cx24116 cfg80211 bcm3510 au8522_dig zl10353 zl10039 zl10036 zd1301_demod ves1x93 ves1820 v4l2_dv_timings tuner_types tua9001 tua6100 ts2020 tea5767 tea5761 tda9887 tda8290 tda827x tda826x tda8261 tda8083 tda665x tda18271c2dd tda18271
[   56.101318]  tda18250 tda18218 tda18212 tda10086 tda10023 tda10021 tc90522 stv6111 stv6110x stv6110 stv0910 stv090x stv0900 stv0367 stv0297 stv0288 stb6100 stb6000 stb0899 si21xx sha256 s921 s5h1432 s5h1420 s5h1411 s5h1409 rng_core rc_core r820t qt1010 qm1d1c0042 qm1d1b0004 pwm_jz4740 nxt6000 mxl5xx mxl5007t mxl5005s mxl301rf mt352 mt312 mt2266 mt2131 mt20xx mt2063 mt2060 mn88443x mc44s803 mc mb86a20s mb86a16 max2165 m88rs6000t m88rs2000 lnbp22 lnbp21 lnbh29 lnbh25 libaes lgs8gl5 lgdt330x lgdt3305 lg2160 ledtrig_camera ledtrig_backlight l64781 kpp ix2505v itd1000 it913x isl6423 isl6421 isl6405 horus3a helene gpio_keys firmware_class fc0013 fc0012 fc0011 ecc ec100 dvb_pll dvb_core drm_panel_orientation_quirks dibx000_common dib3000mb dib0090 dib0070 cxd2880 cxd2841er cxd2820r cxd2099 cx24123 cx24113 cx24110 cx22702 cx22700 cmac cec brcmutil au8522_common atbm8830 ascot2e af9033 a8293
[   56.268085] CPU: 0 UID: 0 PID: 36 Comm: kworker/u4:2 Not tainted 7.1.6-1 #1 PREEMPT
[   56.275401] Hardware name: img,ci20
[   56.278840] Workqueue: events_unbound deferred_probe_work_func
[   56.284648] Stack : 00000000 8017d63c 83fa5a4c 00000004 00000000 00000000 00000000 00000000
[   56.292995]         00000000 00000000 00000000 00000000 00000000 00000001 83fa5a00 de998ae0
[   56.301315]         83fa5a98 00000000 00000000 00000000 00000038 807c2d44 00000000 00000000
[   56.309634]         00000000 00000078 808725a0 6e756f62 00000000 80aa0000 00000000 809fa27c
[   56.317955]         00000000 80a15b38 83fa5b3c c0488b60 00000000 804f783c 00edc85f 00edc89f
[   56.326275]         ...
[   56.328669] Call Trace:
[   56.331094] [<80115ee4>] show_stack+0xb4/0x15c
[   56.335521] [<8010e460>] dump_stack_lvl+0x4c/0x7c
[   56.340200] [<8012a5b8>] __warn+0xb8/0x110
[   56.344272] [<8012a6cc>] warn_slowpath_fmt+0xbc/0x14c
[   56.349389] [<c0488b60>] drm_bridge_get+0x58/0x6c [drm]
[   56.354928] [<c04898b8>] drm_bridge_attach+0x80/0x208 [drm]
[  !56.360397] [<c08ff740>] ingenic_drm_bind.constprop.0+0x68c/0xa18 [ingenic_drm]
[   56.367362] [<8055f148?] platform_probe+0x50/0x8c
[   56.372007] [<8055ccc8>] really_probe+0x164/0x2c4
[   56.376687] [<8055d0f0>] driver_probe_device+0x40/0xcc
[   56.381801] [<8055d1d8>] __device_attach_driver+0x5c/0xdc
[   56.387174] [<8055abb4>] bus_for_each_drv+0xc8/0xf0
[   56.392027] [<8055cb08>] __device_attach+0xe8/0x13c
[   56.396880] [<8055d4e4>] device_initial_probe+0x40/0x6c
[   56.402080] [<8055b7c8>] bus_probe_device+0x34/0xbc
[   56.406933] [<8055c62c>] deferred_probe_work_func+0xb0/0xc8
[   56.412482] [<801448b0>] process_scheduled_works+0x228/0x304
[   56.418114] [<80144be0>] worker_thread+0x254/0x2c4
[   56.422880] [<8014d798>] kthread+0x150/0x158
[   56.427125] [<801108ec>] ret_from_kernel_thread+0x14/0x1c
[   56.432501]
[   56.434018] ---[ end trace 0000000000000000 ]---

Does anyone know how to fix it?

best regards
 Waldemar

Re: imgtec ci20 HDMI broken

[H. Nikolaus Schaller]

Hi Waldemar,

> Am 08.08.2026 um 15:15 schrieb Waldemar Brodkorb <wbx@openadk.org>:
> 
> Hi,
> 
> I recently played a little bit with ci20 devices.
> It seems HDMI is broken in Linux 7.1.6.
> 
> Here is the kernel oops captured via serial console:
> 
> [   54.997593] dw-hdmi-ingenic 10180000.hdmi: Detected HDMI \X controller v1.31a with HDCP (DWC HDMI 3D TX PHY)
> [   55.491338] dw-hdmi-ingenic 10180000.hdmi: registered DesignWare HDMI I2C bus driver
> [   55.899132] [drm] DRM bridge corrupted or not allocated by devm_drm_bridge_alloc()
> [   55.904136] ------------[ cut here ]------------
> [   55.908753] WARNING: lib/refcount.c:25 at drm_bridge_get+0x58/0x6c [drm], CPU#0: kworker/u4:2/36
> [   55.917538] refcount_t: addition on 0; use-after-free.
> [   55.922553] Modules linked in: ingenic_dw_hdmi ingenic_drm hci_uart dw_hdmi v4l2_fwnode drm_dma_helper drm_display_helper drm_client_lib display_connector btbcm b
> rcmfmac_cyw brcmfmac_wcc brcmfmac_bca v4l2_async msi001 fc2580 e4000 drm_kms_helper brcmfmac bluetooth au8522_decoder xc5000 xc4000 xc2028 videodev tuner_simple tda1
> 0071 tda1004x tda10048 stv0299 sp887x sp2 si2165 si2157 rc_zx_irdec rc_xbox_dvd rc_xbox_360 rc_x96max rc_winfast_usbii_deluxe rc_winfast rc_wetek_play2 rc_wetek_hub 
> rc_videostrong_kii_pro rc_videomate_tv_pvr rc_videomate_s350 rc_videomate_m1f rc_vega_s9x rc_twinhan1027 rc_twinhan_dtv_cab_ci rc_tt_1500 rc_trekstor rc_total_media_
> in_hend_02 rc_total_media_in_hand rc_tivo rc_tevii_nec rc_terratec_slim_2 rc_terratec_slim rc_terratec_cinergy_xs rc_terratec_cinergy_s2_hd rc_terratec_cinergy_c_pci
> rc_technisat_usb2 rc_technisat_ts35 rc_tbs_nec rc_tanix_tx5max rc_tanix_tx3mini rc_su3000 rc_streamzap rc_snapstream_firefly rc_siemens_gigaset_rc20 rc_reddo rc_rea
> l_audio_220_32_keys rc_rc6_mce rc_pv951
> [   55.923042]  rc_purpletv rc_proteus_2309 rc_powercolor_real_angel rc_pixelview_new rc_pixelview_mk12 rc_pixelview_002t rc_pixelview rc_pinnacle_pctv_hd rc_pinnacle_grey rc_pinnacle_color rc_pine64 rc_pctv_sedna rc_odroid rc_npgtech rc_norwood rc_nec_terratec_cinergy_xs rc_nebula rc_mygica_utv3 rc_msi_tvanywhere_plus rc_msi_tvanywhere rc_msi_digivox_iii rc_msi_digivox_ii rc_minix_neo rc_medion_x10_or2x rc_medion_x10_digitainer rc_medion_x10 rc_mecool_kiii_pro rc_mecool_kii_pro rc_manli rc_lme2510 rc_leadtek_y04g0051 rc_kworld_plus_tv_analog rc_kworld_pc150u rc_kworld_315u rc_khamsin rc_khadas rc_kaiomy rc_it913x_v2 rc_it913x_v1 rc_iodata_bctv7e rc_imon_rsc rc_imon_pad rc_imon_mce rc_hisi_tv_demo rc_hisi_poplar rc_hauppauge rc_gotview7135 rc_genius_tvgo_a11mce rc_geekbox rc_gadmei_rm008z rc_fusionhdtv_mce rc_flyvideo rc_flydvb rc_eztv rc_evga_indtube rc_encore_enltv2 rc_encore_enltv_fm53 rc_encore_enltv rc_em_terratec rc_dvico_portable rc_dvico_mce rc_dvbsky rc_dtt200u rc_dreambox rc_dntv_live_dvbt_pro
> [   56.012798]  rc_dntv_live_dvb_t rc_dm1105_nec rc_digittrade rc_digitalnow_tinytwin rc_dib0700_rc5 rc_dib0700_nec rc_delock_61959 rc_d680_dmb rc_ct_90405 rc_cinergy_1400 rc_cinergy rc_budget_ci_old rc_behold_columbus rc_behold rc_beelink_mxiii rc_beelink_gs1 rc_azurewave_ad_tu700 rc_avertv_303 rc_avermedia_rm_ks rc_avermedia_m733a_rm_k6 rc_avermedia_m135a rc_avermedia_dvbt rc_avermedia_cardbus rc_avermedia_a16d rc_avermedia rc_ati_x10 rc_ati_tv_wonder_hd_600 rc_asus_ps3_100 rc_asus_pc39 rc_astrometa_t2hybrid rc_apac_viewcomp rc_anysee rc_alink_dtu_m rc_adstech_dvb_t_pci or51211 or51132 nxt200x mxl692 mn88473 mn88472 lgs8gxx ir_kbd_i2c ingenic_rng gpio_ir_tx gpio_ir_recv ecdh_generic ds3000 drxk drxd drx39xyj drm dib9000 dib8000 dib7000p dib7000m dib3000mc cxd2880_spi cx24120 cx24117 cx24116 cfg80211 bcm3510 au8522_dig zl10353 zl10039 zl10036 zd1301_demod ves1x93 ves1820 v4l2_dv_timings tuner_types tua9001 tua6100 ts2020 tea5767 tea5761 tda9887 tda8290 tda827x tda826x tda8261 tda8083 tda665x tda18271c2dd tda18271
> [   56.101318]  tda18250 tda18218 tda18212 tda10086 tda10023 tda10021 tc90522 stv6111 stv6110x stv6110 stv0910 stv090x stv0900 stv0367 stv0297 stv0288 stb6100 stb6000 stb0899 si21xx sha256 s921 s5h1432 s5h1420 s5h1411 s5h1409 rng_core rc_core r820t qt1010 qm1d1c0042 qm1d1b0004 pwm_jz4740 nxt6000 mxl5xx mxl5007t mxl5005s mxl301rf mt352 mt312 mt2266 mt2131 mt20xx mt2063 mt2060 mn88443x mc44s803 mc mb86a20s mb86a16 max2165 m88rs6000t m88rs2000 lnbp22 lnbp21 lnbh29 lnbh25 libaes lgs8gl5 lgdt330x lgdt3305 lg2160 ledtrig_camera ledtrig_backlight l64781 kpp ix2505v itd1000 it913x isl6423 isl6421 isl6405 horus3a helene gpio_keys firmware_class fc0013 fc0012 fc0011 ecc ec100 dvb_pll dvb_core drm_panel_orientation_quirks dibx000_common dib3000mb dib0090 dib0070 cxd2880 cxd2841er cxd2820r cxd2099 cx24123 cx24113 cx24110 cx22702 cx22700 cmac cec brcmutil au8522_common atbm8830 ascot2e af9033 a8293
> [   56.268085] CPU: 0 UID: 0 PID: 36 Comm: kworker/u4:2 Not tainted 7.1.6-1 #1 PREEMPT
> [   56.275401] Hardware name: img,ci20
> [   56.278840] Workqueue: events_unbound deferred_probe_work_func
> [   56.284648] Stack : 00000000 8017d63c 83fa5a4c 00000004 00000000 00000000 00000000 00000000
> [   56.292995]         00000000 00000000 00000000 00000000 00000000 00000001 83fa5a00 de998ae0
> [   56.301315]         83fa5a98 00000000 00000000 00000000 00000038 807c2d44 00000000 00000000
> [   56.309634]         00000000 00000078 808725a0 6e756f62 00000000 80aa0000 00000000 809fa27c
> [   56.317955]         00000000 80a15b38 83fa5b3c c0488b60 00000000 804f783c 00edc85f 00edc89f
> [   56.326275]         ...
> [   56.328669] Call Trace:
> [   56.331094] [<80115ee4>] show_stack+0xb4/0x15c
> [   56.335521] [<8010e460>] dump_stack_lvl+0x4c/0x7c
> [   56.340200] [<8012a5b8>] __warn+0xb8/0x110
> [   56.344272] [<8012a6cc>] warn_slowpath_fmt+0xbc/0x14c
> [   56.349389] [<c0488b60>] drm_bridge_get+0x58/0x6c [drm]
> [   56.354928] [<c04898b8>] drm_bridge_attach+0x80/0x208 [drm]
> [  !56.360397] [<c08ff740>] ingenic_drm_bind.constprop.0+0x68c/0xa18 [ingenic_drm]
> [   56.367362] [<8055f148?] platform_probe+0x50/0x8c
> [   56.372007] [<8055ccc8>] really_probe+0x164/0x2c4
> [   56.376687] [<8055d0f0>] driver_probe_device+0x40/0xcc
> [   56.381801] [<8055d1d8>] __device_attach_driver+0x5c/0xdc
> [   56.387174] [<8055abb4>] bus_for_each_drv+0xc8/0xf0
> [   56.392027] [<8055cb08>] __device_attach+0xe8/0x13c
> [   56.396880] [<8055d4e4>] device_initial_probe+0x40/0x6c
> [   56.402080] [<8055b7c8>] bus_probe_device+0x34/0xbc
> [   56.406933] [<8055c62c>] deferred_probe_work_func+0xb0/0xc8
> [   56.412482] [<801448b0>] process_scheduled_works+0x228/0x304
> [   56.418114] [<80144be0>] worker_thread+0x254/0x2c4
> [   56.422880] [<8014d798>] kthread+0x150/0x158
> [   56.427125] [<801108ec>] ret_from_kernel_thread+0x14/0x1c
> [   56.432501]
> [   56.434018] ---[ end trace 0000000000000000 ]---
> 
> Does anyone know how to fix it?
> 
> best regards
> Waldemar
> 

I am not sure if I did see the same error but I recently did a fix for bridge allocation (not submitted):

https://github.com/goldelico/letux-kernel/commit/9d039bd064094b176825da9f471e9c4447674703

Please let me know if it works. Then we can post it.

Best regards,
Nikolaus

Re: imgtec ci20 HDMI broken

[Waldemar Brodkorb]

Hi Nikolaus,
H. Nikolaus Schaller wrote,

> Hi Waldemar,
> 
> > Am 08.08.2026 um 15:15 schrieb Waldemar Brodkorb <wbx@openadk.org>:
> > 
> > Hi,
> > 
> > I recently played a little bit with ci20 devices.
> > It seems HDMI is broken in Linux 7.1.6.
> > 
> > Here is the kernel oops captured via serial console:

[ removed oops ]
 
> I am not sure if I did see the same error but I recently did a fix for bridge allocation (not submitted):
> 
> https://github.com/goldelico/letux-kernel/commit/9d039bd064094b176825da9f471e9c4447674703
> 
> Please let me know if it works. Then we can post it.

Yes it works! Please post it. Thank you.
I have seen your Linux fork Letux with audio support for CI20, are
you planning to bring this upstream, too?

best regards
 Waldemar

Re: imgtec ci20 HDMI broken

[H. Nikolaus Schaller]

> Am 09.08.2026 um 14:33 schrieb Waldemar Brodkorb <wbx@openadk.org>:
> 
> Hi Nikolaus,
> H. Nikolaus Schaller wrote,
> 
>> Hi Waldemar,
>> 
>>> Am 08.08.2026 um 15:15 schrieb Waldemar Brodkorb <wbx@openadk.org>:
>>> 
>>> Hi,
>>> 
>>> I recently played a little bit with ci20 devices.
>>> It seems HDMI is broken in Linux 7.1.6.
>>> 
>>> Here is the kernel oops captured via serial console:
> 
> [ removed oops ]
> 
>> I am not sure if I did see the same error but I recently did a fix for bridge allocation (not submitted):
>> 
>> https://github.com/goldelico/letux-kernel/commit/9d039bd064094b176825da9f471e9c4447674703
>> 
>> Please let me know if it works. Then we can post it.
> 
> Yes it works! Please post it. Thank you.

Great to know. I will add some Tested-by:

Please remind me if I forget to post it in the next weeks...

> I have seen your Linux fork Letux with audio support for CI20, are
> you planning to bring this upstream, too?

Well not really as it likely has not been tested beyond compile tests (at least I am not aware of).

But it is good to learn that there are still some CI20 boards and users around...

BR,
Nikolaus