fwupd/plugins/parade-lspcon/README.md
2021-07-18 14:42:47 -05:00

55 lines
1.8 KiB
Markdown

# Parade LSPCON
## Introduction
This plugin updates the firmware of HDMI level shifter and protocol converter
(LSPCON) devices made by Parade Technologies, such as the PS175.
These devices communicate over I²C, via either the DisplayPort aux channel or a
dedicated bus- this plugin uses a dedicated bus declared by system firmware for,
flashing, and reads the device firmware version from DPCD. Quirks specify the
DisplayPort bus over which DPCD is read for a given system.
Firmware is stored on an external flash attached to an SPI bus on the device.
The attached flash is assumed to be compatible with the W25Q20 series of
devices, in particular supporting a 64k Block Erase command (0xD8) with 24-bit
address and Write Enable for Volatile Status Register (0x05).
## Firmware Format
The device firmware is in an unspecified binary format that is written directly
to an inactive partition of the Flash attached to the device.
This plugin supports the following protocol ID:
* com.paradetech.ps176
## GUID Generation
The plugin uses a custom DeviceInstanceId value derived from the device name
provided by system firmware and read from sysfs, such as:
* `PARADE-LSPCON\NAME_1AF80175:00`
* `PARADE-LSPCON\NAME_1AF80175:00&FAMILY_Google_Hatch`
## Quirk Use
This plugin uses the following plugin-specific quirks:
### ParadeLspconAuxDeviceName
The sysfs name of the `drm_dp_aux_dev` over which device version should be read.
Since: 1.6.2
## Vendor ID security
The vendor ID is specified by system firmware (such as ACPI tables) and is
part of the device's name as read from sysfs.
## External Interface Access
This plugin requires access to the DisplayPort aux channel to read DPCD, such
as `/dev/drm_dp_aux0` as well as the i2c bus attached to the device, such as
`/dev/i2c-7`.