Flashing firmware on Android is slow

[dlech]

Describe the bug
Flashing firmware on City Hub and Technic Hub using Android OS takes longer than on other platforms.

To reproduce
Steps to reproduce the behavior:

1. Get a stopwatch
2. Time firmware flashing on non-Android
3. Time firmware on Android

Expected behavior
Times should be reasonably close.

[dlech]

As discussed in #403 (comment), this is caused by a bug in Chromium where the MTU is negotiated to the minimum value on Android and higher values on other platforms.

Upstream bug is https://crbug.com/1164621. There has been a preliminary patch proposed there, so we just need to get it officially submitted and merged.

[dlech]

This has been fixed in Chromium 98.

We could modify https://github.com/pybricks/pybricks-code/blob/e7d44ea9a9195bc2a612a22acd84e09dfc048dac/src/firmware/sagas.ts#L382 to check for this version or just wait until most of the world has upgraded and remove the Android check there altogether.

[dlech]

Fixed in pybricks/pybricks-code@614e0b0

[laurensvalk]

What is the behavior on older phones after this fix? Just slow or broken?

[dlech]

The age of the phone doesn't matter, only the version of Chrome. Firmware will fail to flash versions prior to 98 which was released over a year ago.

[laurensvalk]

Ah. I was thinking of Android not getting updates on older phones., but indeed Chrome should still be getting updates on those.