[SRU][Q/R][PATCH 0/1] Could not output video from type-c to VGA adapter

[Stefan Bader]

On 26/12/2025 04:44, AceLan Kao wrote:
> From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2133143
> 
> [Impact]
> Plugged the Lenovo USB-C to VGA adapter or Dell DA310 hub to thunderbolt 5
> port, the communication through AUX timed out, and there is no video
> output to the VGA monitor
> 
> i915 0000:00:02.0: [drm:drm_dp_dpcd_read [drm_display_helper]] AUX USBC4/DDI TC4/PHY TC4: 0x00000 AUX -> (ret=-110)
> 
> [Fix]
> https://lkml.org/lkml/2025/11/27/193
> v2 - https://lore.kernel.org/lkml/20251204024647.1462866-1-acelan.kao@canonical.com/T/#u
> 
> [Test]
> 1. Find a device with TB5 port
> 2. Plug a VGA monitor to Lenovo USB-C to VGA adapter[17ef:7217] or Dell DA310[413c:c010]
> 3. Plug the adapter/hub to the TB5 port
> 4. The external monitor should work as expected.
> 
> [Where problems could occur]
> It handles the fail case and doesn't affect the code path if it already works. No regression.
> 
> Chia-Lin Kao (AceLan) (1):
>    UBUNTU: SAUCE: drm/dp: Add byte-by-byte fallback for broken USB-C
>      adapters
> 
>   include/drm/display/drm_dp_helper.h | 57 +++++++++++++++++++----------
>   1 file changed, 37 insertions(+), 20 deletions(-)
> 

I see no justification why this is done as a SAUCE patch and not 
properly via upstream.

-Stefan
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