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Allow baud rates of 1,228,800 and 1,843,200 on CP2101/2/3 usb-serial adapters.

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The datasheets for these chips claim the maximum is 921,600, but testing
shows these two higher rates also work (but no rates above 921,600 other
than these two work; these represent dividing the base buad clock by 3 and 2
respectively).
This commit is contained in:
Ian Lepore 2019-12-09 21:55:44 +00:00
parent d3eca31ea6
commit 24fa2fba9d
2 changed files with 11 additions and 2 deletions
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7
share/man/man4/uslcom.4
View File

@ -16,7 +16,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd April 26, 2017
.Dd December 9, 2019
.Dt USLCOM 4
.Os
.Sh NAME
@ -43,6 +43,11 @@ The
.Nm
driver supports Silicon Laboratories CP2101/CP2102/CP2103/CP2104/CP2105
based USB serial adapters.
.Pp
The datasheets for the CP2101/CP2102/CP2103 list the maximum
supported baud rate as 921,600.
Empirical testing has shown that the rates 1,228,800 and 1,843,200 also work,
at least on some hardware, so the driver allows setting those rates.
.Sh HARDWARE
The following devices should work with the
.Nm

6
sys/dev/usb/serial/uslcom.c
View File

@ -624,7 +624,11 @@ uslcom_pre_param(struct ucom_softc *ucom, struct termios *t)
case USLCOM_PARTNUM_CP2102:
case USLCOM_PARTNUM_CP2103:
default:
maxspeed = 921600;
/*
* Datasheet for cp2102 says 921600 max. Testing shows that
* 1228800 and 1843200 work fine.
*/
maxspeed = 1843200;
break;
}
if (t->c_ospeed <= 0 || t->c_ospeed > maxspeed)