svn commit: r333999 - head/sys/dev/usb/serial

[Andriy Gapon]

Author: avg
Date: Mon May 21 20:59:15 2018
New Revision: 333999
URL: https://svnweb.freebsd.org/changeset/base/333999

Log:
  uchcom: add a hardware configuration tweak seen in Linux code
  
  Reviewed by:	hselasky
  MFC after:	2 weeks

Modified:
  head/sys/dev/usb/serial/uchcom.c

Modified: head/sys/dev/usb/serial/uchcom.c
==============================================================================
--- head/sys/dev/usb/serial/uchcom.c	Mon May 21 20:58:06 2018	(r333998)
+++ head/sys/dev/usb/serial/uchcom.c	Mon May 21 20:59:15 2018	(r333999)
@@ -618,8 +618,12 @@ uchcom_set_baudrate(struct uchcom_softc *sc, uint32_t 
 	if (uchcom_calc_divider_settings(&dv, rate))
 		return;
 
+	/*
+	 * According to linux code we need to set bit 7 of UCHCOM_REG_BPS_PRE,
+	 * otherwise the chip will buffer data.
+	 */
 	uchcom_write_reg(sc,
-	    UCHCOM_REG_BPS_PRE, dv.dv_prescaler,
+	    UCHCOM_REG_BPS_PRE, dv.dv_prescaler | 0x80,
 	    UCHCOM_REG_BPS_DIV, dv.dv_div);
 	uchcom_write_reg(sc,
 	    UCHCOM_REG_BPS_MOD, dv.dv_mod,