[usbdev] Clean up confusing uses of "differential"
Explicitly refer to a receiver wherever "differential" is used with
"rx".
Previously, the term on RX would mean that an *external* differential
receiver would be used, delivering a *single-ended* data signal to the
IP. However, this top-level definition causes too much confusion.
Similarly, for TX, avoid using "differential" altogether, as neither the
driver nor the signals are truly differential. Instead, refer to the two
interfaces by the component signal names.
Signed-off-by: Alexander Williams <awill@google.com>
diff --git a/sw/device/lib/dif/dif_usbdev.h b/sw/device/lib/dif/dif_usbdev.h
index 46b7240..4c7a57c 100644
--- a/sw/device/lib/dif/dif_usbdev.h
+++ b/sw/device/lib/dif/dif_usbdev.h
@@ -123,9 +123,10 @@
*/
typedef struct dif_usbdev_config {
/**
- * Use the differential rx signal instead of the single-ended signals.
+ * Activate the single-ended D signal for detecting K and J symbols, for use
+ * with a differential receiver.
*/
- dif_toggle_t differential_rx;
+ dif_toggle_t have_differential_receiver;
/**
* Use the TX interface with D and SE0 signals instead of Dp/Dn, for use with
* certain transceivers.
