[Bug 111997] [CI][RESUME]igt at igt@kms_vblank at pipe-c-wait-busy-hang|igt at kms_vblank@pipe-c-ts-continuation-idle-hang - dmesg-warn - *ERROR* [CONNECTOR:291:HDMI-A-1] Failed to configure sink scrambling/TMDS bit clock ratio

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=111997

--- Comment #3 from shashank.sharma at intel.com <shashank.sharma at intel.com> ---
As Ville mentioned, we are timing out while disabling the scrambling and
setting the SCDC ratio here, as there is no response to the I2C SCDC write from
the sink device. But I am worried about a few more things here: 

- We are seeing a DVI adapter onboard detected from VBT (why ?) which blocks
the max pixel clock supported to 165 Mhz. 

[drm:intel_hdmi_set_edid [i915]] Assuming DP dual-mode adaptor presence based
on VBT
<7>[   11.313384] [drm:intel_hdmi_set_edid [i915]] DP dual-mode adaptor (type 1
DVI) detected (max TMDS clock: 165000 kHz)

- This means we will never have to disable scrambling or set the TMDS clock
ratio to 1/10, as it gets set only when the video mode's clock is > 340 Mhz. We
are pruning out all the modes with clock > 165Mhz, so we will never hit a
situation where we have to disable scrambling, as it will never be enabled. 

- Probably we can add a check in intel_hdmi_handle_sink_scrambling() function
no simply return when there is a DVI adapter. I will see if I can add a patch
for that. Probably a run with a proper VBT will also help.

- But in any case, this bug should be kept at a lower priority, as there is no
need to disable scrambling here at all. 

- Shashank

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