Glasgow Embedded / Glasgow - History

support.endpoint: introduce queue_size argument

This limits the receive queue size and pushes back on the underlying
transport when the receive queue is full.

access.direct.demultiplexer: introduce software side queue length limits

This implements a configurable thireshold for FIFO data queueing on the
Python side, with pushback. Previously, any data was buffered eagerly,
e.g. an applet sending data on the hardware side and never receiving
it on the software side (or vice versa) would cause the data to pile up
in Python buffers at full speed, with no memory usage limit.

With this patch, the user may specify queue size limits. These limits
are not strict, but rather just thresholds for pushback. If the user
configures a 1MB FIFO limit and writes 100MB, the write will complete
immediately, but a subsequent write will block until 99MB of data has
been successufully queued with the USB subsystem (URB buffers do not
count towards the limit). Similarly, configuring a 1MB read limit
will allow a URB completion that crosses that threshold to complete,
but no further URBs will be re-queued until the application reads data
from the FIFO, eventually causing the on-device FIFO to fill up and
stop accepting writes from the gateware.

applet.video.ws2812_output: reduce reset time to 300µs as documented

applet.video.ws2812_output: use non-blocking flush

We need to make sure that all video data will make it to the Glasgow
in a timely manner, to avoid "tearing" the frame (the LEDs cannot
handle gaps longer than a few microseconds in the data stream without
triggering a premature latch/reset), but we don't necessarily want to
wait for the data to actually be sent.

access.direct.demultiplexer: introduce non-blocking flushes

flush([wait=True]) ensures that all written data has been sent to
the device. flush(wait=False) on the other hand ensures that all
written data has been queued as USB URBs, but does not wait for them
to complete.

Use flush(wait=False) to ensure that every last byte of queued data
will make it to the device in a timely manner, without stalling
the entire USB transfer pipeline.

applet.program.ice40_sram: simplify. NFC.

Reset pin is required anyway.

applet.program.nrf24l: unmark as preview.

Seems to work OK.

applet.interface.jtag_pinout: support more than 8 pins.

applet.interface.jtag_probe: fix scan_xr_length on overlong XR.