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[PATCH 0/4] usb-serial: xHCI and timeout fixes

From: Jason Andryuk
Subject: [PATCH 0/4] usb-serial: xHCI and timeout fixes
Date: Thu, 12 Mar 2020 08:55:19 -0400

This patch series includes two fixes for usb-serial.

The first is a data corruption issue with xHCI controllers.  The FTDI
data packets need to have a 2 byte header start every 64 bytes of packet
data.  For EHCI this is not a problem since USBPacket size is 64, so
only 1 such chunk fits in a packet.  xHCI controllers supply 512 byte
USBPackets, and usb-serial would only write a single header.  This
confuses drivers since they interpret some data bytes as header bytes.
Chunk the data with headers at every 64 byte offset.

To allow full use of the 512 USBPackets, increase the buffer size to 512
- 2 * 8 = 496 bytes.

A second fix is to set the FTDI_THRE (Transmitter Holding Register) and
FTDI_TEMT (Transmitter Empty) status bits in a GetModemStat response.
This makes the linux driver happy when closing the device and avoids a
30 second timeout.

Jason Andryuk (4):
  usb-serial: Move USB_TOKEN_IN into a helper function
  usb-serial: chunk data to wMaxPacketSize
  usb-serial: Increase receive buffer to 496
  usb-serial: Fix timeout closing the device

 hw/usb/dev-serial.c | 92 +++++++++++++++++++++++++++------------------
 1 file changed, 56 insertions(+), 36 deletions(-)


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