From 7f0d0f7f5039e92e1462502c79c17f8cb5c9e420 Mon Sep 17 00:00:00 2001
From: uaa <uaa@openbsd.org>
Date: Wed, 26 Jan 2022 12:05:33 +0000
Subject: [PATCH] shrink uca.ibufsize from UCHCOMIBUFSIZE to wMaxPacketSize of
 bulk-in pipe

USB transaction is finished when whole requested data has transferred,
or short packet (the size is less than wMaxPacketSize) has sent.

UCHCOMIBUFSIZE(256) was multiply of wMaxPacketSize(32). When CH340 sends
exact wMaxPacketSize byte packet, this will cause Rx jam problem
due to transaction is not finished.

Now uca.ibufsize is same as wMaxPacketSize to avoid this problem.

ok kevlo@
---
 sys/dev/usb/uchcom.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/sys/dev/usb/uchcom.c b/sys/dev/usb/uchcom.c
index 247f9a55c3d..654b891542c 100644
--- a/sys/dev/usb/uchcom.c
+++ b/sys/dev/usb/uchcom.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uchcom.c,v 1.31 2021/11/19 07:58:34 dlg Exp $	*/
+/*	$OpenBSD: uchcom.c,v 1.32 2022/01/26 12:05:33 uaa Exp $	*/
 /*	$NetBSD: uchcom.c,v 1.1 2007/09/03 17:57:37 tshiozak Exp $	*/
 
 /*
@@ -113,7 +113,6 @@ int	uchcomdebug = 0;
 #define UCHCOM_RESET_VALUE	0x501F	/* line mode? */
 #define UCHCOM_RESET_INDEX	0xD90A	/* baud rate? */
 
-#define UCHCOMIBUFSIZE 256
 #define UCHCOMOBUFSIZE 256
 
 struct uchcom_softc
@@ -141,6 +140,7 @@ struct uchcom_softc
 struct uchcom_endpoints
 {
 	int		ep_bulkin;
+	int		ep_bulkin_size;
 	int		ep_bulkout;
 	int		ep_intr;
 	int		ep_intr_size;
@@ -293,9 +293,9 @@ uchcom_attach(struct device *parent, struct device *self, void *aux)
 	uca.portno = UCOM_UNK_PORTNO;
 	uca.bulkin = endpoints.ep_bulkin;
 	uca.bulkout = endpoints.ep_bulkout;
-	uca.ibufsize = UCHCOMIBUFSIZE;
+	uca.ibufsize = endpoints.ep_bulkin_size;
 	uca.obufsize = UCHCOMOBUFSIZE;
-	uca.ibufsizepad = UCHCOMIBUFSIZE;
+	uca.ibufsizepad = endpoints.ep_bulkin_size;
 	uca.opkthdrlen = 0;
 	uca.device = dev;
 	uca.iface = sc->sc_iface;
@@ -349,7 +349,7 @@ int
 uchcom_find_endpoints(struct uchcom_softc *sc,
     struct uchcom_endpoints *endpoints)
 {
-	int i, bin=-1, bout=-1, intr=-1, isize=0;
+	int i, bin=-1, bout=-1, intr=-1, binsize=0, isize=0;
 	usb_interface_descriptor_t *id;
 	usb_endpoint_descriptor_t *ed;
 
@@ -370,6 +370,7 @@ uchcom_find_endpoints(struct uchcom_softc *sc,
 		} else if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_IN &&
 			   UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK) {
 			bin = ed->bEndpointAddress;
+			binsize = UGETW(ed->wMaxPacketSize);
 		} else if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_OUT &&
 			   UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK) {
 			bout = ed->bEndpointAddress;
@@ -402,6 +403,7 @@ uchcom_find_endpoints(struct uchcom_softc *sc,
 	endpoints->ep_intr = intr;
 	endpoints->ep_intr_size = isize;
 	endpoints->ep_bulkin = bin;
+	endpoints->ep_bulkin_size = binsize;
 	endpoints->ep_bulkout = bout;
 
 	return 0;
-- 
2.20.1