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Exporsing HotPlugDetect(HPD) helps userspace to infer HPD state as defined by VESA DisplayPort Alt Mode on USB Type-C Standard. This allows userspace to notify users for self help, for instance, to hint user that the display port cable is probably detached (or) the display port sink (viz., monitors ect.,) is un-powered. Also helps to debug issues reported from field. This change adds an additional attribute "hpd" to the existing "displayport" attributes. VESA DisplayPort Alt Mode on USB Type-C Standard defines how HotPlugDetect(HPD) shall be supported on the USB-C connector when operating in DisplayPort Alt Mode. This is a read only node which reflects the current state of HPD. Valid values: - 1 when HPD’s logical state is high (HPD_High) - 0 when HPD’s logical state is low (HPD_Low) Signed-off-by: Badhri Jagan Sridharan <badhri@google.com> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Link: https://lore.kernel.org/r/20221211193755.1392128-1-badhri@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
64 lines
2.5 KiB
Text
64 lines
2.5 KiB
Text
What: /sys/bus/typec/devices/.../displayport/configuration
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Date: July 2018
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Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
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Description:
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Shows the current DisplayPort configuration for the connector.
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Valid values are USB, source and sink. Source means DisplayPort
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source, and sink means DisplayPort sink.
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All supported configurations are listed as space separated list
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with the active one wrapped in square brackets.
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Source example:
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USB [source] sink
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The configuration can be changed by writing to the file
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Note. USB configuration does not equal to Exit Mode. It is
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separate configuration defined in VESA DisplayPort Alt Mode on
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USB Type-C Standard. Functionally it equals to the situation
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where the mode has been exited (to exit the mode, see
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Documentation/ABI/testing/sysfs-bus-typec, and use file
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/sys/bus/typec/devices/.../active).
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What: /sys/bus/typec/devices/.../displayport/pin_assignment
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Date: July 2018
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Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
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Description:
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VESA DisplayPort Alt Mode on USB Type-C Standard defines six
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different pin assignments for USB Type-C connector that are
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labeled A, B, C, D, E, and F. The supported pin assignments are
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listed as space separated list with the active one wrapped in
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square brackets.
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Example:
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C [D]
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Pin assignment can be changed by writing to the file. It is
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possible to set pin assignment before configuration has been
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set, but the assignment will not be active before the
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connector is actually configured.
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Note. As of VESA DisplayPort Alt Mode on USB Type-C Standard
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version 1.0b, pin assignments A, B, and F are deprecated. Only
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pin assignment D can now carry simultaneously one channel of
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USB SuperSpeed protocol. From user perspective pin assignments C
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and E are equal, where all channels on the connector are used
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for carrying DisplayPort protocol (allowing higher resolutions).
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What: /sys/bus/typec/devices/.../displayport/hpd
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Date: Dec 2022
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Contact: Badhri Jagan Sridharan <badhri@google.com>
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Description:
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VESA DisplayPort Alt Mode on USB Type-C Standard defines how
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HotPlugDetect(HPD) shall be supported on the USB-C connector when
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operating in DisplayPort Alt Mode. This is a read only node which
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reflects the current state of HPD.
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Valid values:
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- 1: when HPD’s logical state is high (HPD_High) as defined
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by VESA DisplayPort Alt Mode on USB Type-C Standard.
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- 0 when HPD’s logical state is low (HPD_Low) as defined by
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VESA DisplayPort Alt Mode on USB Type-C Standard.
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