drm/i915/ddi: only call shutdown hooks for valid encoders

commit 60a43ecb upstream.

DDI might be HDMI or DP only, leaving the other encoder
uninitialized. Calling the shutdown hook on an uninitialized encoder may
lead to a NULL pointer dereference. Check the encoder types (and thus
validity via the DP output_reg or HDMI hdmi_reg checks) before calling
the hooks.

Reported-and-tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Closes: https://lore.kernel.org/r/20241031105145.2140590-1-senozhatsky@chromium.org


Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/8b197c50e7f3be2bbc07e3935b21e919815015d5.1735568047.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>