libfprint-patch-build

name	libfprint-patch-build
description	Use when adapting the EH575 work into an EH577 libfprint driver, editing the local WIP driver files, comparing against upstream libfprint Egis drivers, or building libfprint to validate the EH577 port.

Patch And Build Libfprint

Use this when the task is in the driver porting path rather than the live probe path.

Read first

Read only what is needed for the current edit:

• AGENTS.md
• wip-libfprint/drivers/egis0577.c
• wip-libfprint/drivers/egis0577.h
• refs/EgisTec-EH575/libfprint.patch
• refs/libfprint/libfprint/drivers/egis0570.c
• refs/libfprint/libfprint/drivers/egismoc/egismoc.c

Porting stance

Default assumptions:

• EH577 should be treated as EH575-family hardware
• start from the EH575 patch structure, not from scratch
• keep response handling flexible where state bytes have already varied
• do not model EH577 as egismoc unless new endpoint or packet evidence forces that

Preferred edit order

1. Update device IDs and driver registration.
2. Keep sequence tables aligned with the known-good EH575 replay path.
3. Relax reply parsing where state bytes are known to vary.
4. Preserve room for later interrupt integration instead of assuming interrupts are unused.
5. Validate the edited driver against captured logs and dumps before broad refactors.

Build and Testing Workflow

The upstream reference tree is under refs/libfprint/ and uses Meson.

1. Local Build & CLI Testing (Development)

For rapid development, avoid installing to the system. Build locally and test using the provided helper script which injects LD_LIBRARY_PATH:

meson setup refs/libfprint/build refs/libfprint
ninja -C refs/libfprint/build

# Sync your WIP files before building!
cp wip-libfprint/egis0577.c refs/libfprint/libfprint/drivers/egis0577.c
cp wip-libfprint/egis0577.h refs/libfprint/libfprint/drivers/egis0577.h

# Run the CLI test suite
./tools/enroll_identify.sh

2. System Installation & GUI E2E Testing (Final Verification)

When validating the driver for actual system usage (e.g., GNOME Settings integration with fprintd), the default /usr/local prefix is insufficient. The driver MUST be installed directly into the system OS library paths.

Use the provided system installer script, which automatically configures Meson with --prefix=/usr --libdir=lib/x86_64-linux-gnu, builds the driver, installs it with sudo, and restarts the fprintd system service:

./tools/install-to-system.sh

After running the install script, the end-user can navigate to their OS Settings (e.g., GNOME Settings -> Users -> Fingerprint Login) to verify E2E enrollment and identification.

Validation checklist

Before calling the patch good, verify:

• the code still matches the observed endpoint layout
• packet and response handling still fit the successful EH575 replay logs
• no logic assumes fixed values for bytes already seen to vary
• build output is clean enough to distinguish new errors from existing upstream noise

When blocked

If a driver change depends on behavior not yet captured, switch back to the probe workflow and gather the missing evidence instead of guessing protocol details.