Re: drm/i915: Disconnect PHYs left connected by BIOS on disabled ports

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On 2/17/22 16:22, Imre Deak wrote:
BIOS may leave a TypeC PHY in a connected state even though the
corresponding port is disabled. This will prevent any hotplug events
from being signalled (after the monitor deasserts and then reasserts its
HPD) until the PHY is disconnected and so the driver will not detect a
connected sink. Rebooting with the PHY in the connected state also
results in a system hang.

Fix the above by disconnecting TypeC PHYs on disabled ports.

Before commit 64851a32c463e5 the PHY connected state was read out even
for disabled ports and later the PHY got disconnected as a side effect
of a tc_port_lock/unlock() sequence (during connector probing), hence
recovering the port's hotplug functionality.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5014
Fixes: 64851a32c463 ("drm/i915/tc: Add a mode for the TypeC PHY's disconnected state")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.16+
Cc: José Roberto de Souza <jose.souza@xxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>

Issue seen on my Lenovo ThinkPad L14 Gen 2 with Intel TigerLake-LP GT2 (Iris Xe) using Arch Linux, after upgrading the kernel from 5.15.3 and 5.16.0. Bisected my way to isolate commit 64851a32 as the first bad commit. Applying Imre's patch onto drm-tip reliably fixes the issue for me.

Reported-and-tested-by: Philipp Gortan <philipp@xxxxxxxxxx>

Thanks!
Philipp



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