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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Paul=20Gr=C3=B6=C3=9Fel?= <pb.g@gmx.de>,
        Willy Tarreau <w@1wt.eu>, Johan Hovold <johan@kernel.org>
Subject: [PATCH 4.4 02/10] Revert "USB: serial: ch341: fix character loss at high transfer rates"
Date:   Wed,  1 Sep 2021 14:26:16 +0200
Message-Id: <20210901122248.133229336@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit df7b16d1c00ecb3da3a30c999cdb39f273c99a2f upstream.

This reverts commit 3c18e9baee0ef97510dcda78c82285f52626764b.

These devices do not appear to send a zero-length packet when the
transfer size is a multiple of the bulk-endpoint max-packet size. This
means that incoming data may not be processed by the driver until a
short packet is received or the receive buffer is full.

Revert back to using endpoint-sized receive buffers to avoid stalled
reads.

Reported-by: Paul Größel <pb.g@gmx.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214131
Fixes: 3c18e9baee0e ("USB: serial: ch341: fix character loss at high transfer rates")
Cc: stable@vger.kernel.org
Cc: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20210824121926.19311-1-johan@kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/serial/ch341.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -585,7 +585,6 @@ static struct usb_serial_driver ch341_de
 		.owner	= THIS_MODULE,
 		.name	= "ch341-uart",
 	},
-	.bulk_in_size      = 512,
 	.id_table          = id_table,
 	.num_ports         = 1,
 	.open              = ch341_open,