AprilNEA/OpenLogi · error

DPI write failed: requested

Error message

DPI write failed: requested {target}, device still reports {before}

What it means

Round-trip verification failure in `openlogi diag dpi`: the set_dpi write was accepted, but the post-write read-back returns exactly the pre-write DPI, meaning the device applied nothing. Because the requested target was already validated against the device's supported list and is guaranteed different from the current value, a no-op read-back can only indicate a device/firmware fault (write silently ignored), not a bad input, so the diagnostic bails instead of reporting success.

Solutions

1. Re-run the diagnostic — transient HID++ write failures can present as silent no-ops
2. Power-cycle or re-pair the device and retry
3. Try a different supported --target value to see whether all writes or just one step are ignored
4. Compare with other diag round-trips to isolate whether the device's write path is generally broken

When it happens

Trigger: Thrown at crates/openlogi-cli/src/cmd/diag/dpi.rs:76 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of AprilNEA/OpenLogi@e846e6f4b4 (2026-09-13). Data as JSON: /api/errors/5d2d6ca5b2f9f917. Report an issue: GitHub.

Appendix: source

Thrown at crates/openlogi-cli/src/cmd/diag/dpi.rs:76

        return Ok(());
    }

    println!("  writing DPI: {target}");
    openlogi_hid::set_dpi(&route, target)
        .await
        .context("write DPI")?;

    let after = openlogi_hid::get_dpi(&route)
        .await
        .context("read DPI after write")?;
    println!("  read-back DPI: {after}");

    // `target` is always a device-reported value, so a mismatch means the
    // device adjusted it — fine if it landed on another supported value, but a
    // no-op write (`after == before`) or an off-list read-back is a real fault.
    // (`target != before` is guaranteed by the early return above.)
    if after == before {
        anyhow::bail!("DPI write failed: requested {target}, device still reports {before}");
    }
    if after != target {
        if info.capabilities.contains(after) {
            println!("  note: device snapped {target} → {after}");
        } else {
            anyhow::bail!(
                "DPI write failed: requested {target}, device reports {after} \
                 which is not in its supported list"
            );
        }
    }

    println!("  restoring DPI: {before}");
    openlogi_hid::set_dpi(&route, before)
        .await
        .context("restore DPI")?;

    println!("✓ DPI round-trip OK");

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