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authorBrian Cully <bjc@kublai.com>2019-08-01 22:04:31 -0400
committerBrian Cully <bjc@kublai.com>2019-08-01 22:04:31 -0400
commit7dc75aefb6785ac69898d3262507bf462946a696 (patch)
tree44927a50070579319f2d65e3025e357302f00694
parentde3e8606c3bc199dfe417d3737c37fc898dc0442 (diff)
downloadsamd21-demo-7dc75aefb6785ac69898d3262507bf462946a696.tar.gz
samd21-demo-7dc75aefb6785ac69898d3262507bf462946a696.zip
Add TODO file.
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+* Create trait library.
+We'll need traits for both the USB host driver and USB
+device/interface drivers.
+
+Right now everything's pretty tied together with no clean separation,
+but aside from a couple painful points it shouldn't be *too* hard to
+separate.
+
+So far we've managed to avoid needing an allocator, but that's
+probably gonig to be impossible in the general sense. However, it may
+be possible to limit allocation to just the device driver level, which
+is more pleasing since it's more fungible.
+
+* Use trait library for SAMD21/51 host implementation.
+Add features for max devices/endpoints to save on memory.
+
+* Use trait library for boot protocol keyboard driver.
+This code currently lives in `device.rs` and is also a disaster.
+** Parse configuration descriptors.
+
+
+* control/in/out_transfer probably shouldn't take a `&mut T`.
+This is pretty unsafe for functions that shouldn't be unsafe. Instead
+we should take a `&mut [u8]` and let callers be unsafe if they want
+0-copy. This would also allow us to more easily use variable-length
+responses in the few cases those are used.
+
+* Use channel for interrupt -> task messages.
+Currently we use a static mut which holds the latest event. This was
+done for expediency to try and get somethnig working and this was
+working in Arduino. It's also massively wrong in the general case and
+overflowing with race conditions.
+
+A channel will allow us to deterministically walk events and make sure
+everything's ordered properly.
+
+* Clean up pipe descriptor stuff.
+There's a bunch of unsafe functions that can be made safe.
+
+* Some SVD patches needed for SAMD21/51.
+There's a lot of `unsafe` code where there shouldn't be, because the
+SVD files are lacking.
+
+* Stop passing millis function around.
+This is horrible, but currently necessary because there are places
+where we need to loop on a timer at it needs to be
+hardware-independent.
+
+If the USB host library can be made asynchronouse, we could instead
+pass a current timestamp around and use that for delays where
+necessary.
+
+As a last resort, there's a countdown timer trait in embedded-hal that
+may be useful.
+
+* Tighten up timings on requests.
+There are a few timer checks on USB requests, but not necessarily of
+the right duration nor subdivided correctly. For instance, the
+setup-with-data cycle has requirements on total duration as well as
+per-packet duration, but currently we're only using the total.