USB: ftdi_sio: fix hi-speed device packet size calculation
Added a function to set the packet size to be used based on the value from the
device endpoint descriptor. The FT2232H and FT4232H hi-speed devices will have
wMaxPacketSize of 512 bytes when connected to a USB 2.0 hi-speed host, but will
use alternative descriptors with wMaxPacketSize of 64 bytes if connected to a
USB 1.1 host or hub. All other FTDI devices have wMaxPacketSize of 64 bytes,
except some FT232R and FT245R devices which customers have mistakenly
programmed to have wMaxPacketSize of 0 - this is an error and will be
overridden to use wMaxPacketSize of 64 bytes. The packet size used is
important as it determines where the driver removes the status bytes from the
incoming data. If it is incorrect, it will lead to data corruption.
Signed-off-by: Mark J. Adamson <mark.adamson@ftdichip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 80ccfa1..74cc3c8 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -95,6 +95,7 @@
unsigned long tx_bytes;
unsigned long tx_outstanding_bytes;
unsigned long tx_outstanding_urbs;
+ unsigned short max_packet_size;
};
/* struct ftdi_sio_quirk is used by devices requiring special attention. */
@@ -703,7 +704,6 @@
/* Constants for read urb and write urb */
#define BUFSZ 512
-#define PKTSZ 64
/* rx_flags */
#define THROTTLED 0x01
@@ -1296,6 +1296,45 @@
}
+/* Determine the maximum packet size for the device. This depends on the chip
+ * type and the USB host capabilities. The value should be obtained from the
+ * device descriptor as the chip will use the appropriate values for the host.*/
+static void ftdi_set_max_packet_size(struct usb_serial_port *port)
+{
+ struct ftdi_private *priv = usb_get_serial_port_data(port);
+ struct usb_serial *serial = port->serial;
+ struct usb_device *udev = serial->dev;
+
+ struct usb_interface *interface = serial->interface;
+ struct usb_endpoint_descriptor *ep_desc = &interface->cur_altsetting->endpoint[1].desc;
+
+ unsigned num_endpoints;
+ int i = 0;
+
+ num_endpoints = interface->cur_altsetting->desc.bNumEndpoints;
+ dev_info(&udev->dev, "Number of endpoints %d\n", num_endpoints);
+
+ /* NOTE: some customers have programmed FT232R/FT245R devices
+ * with an endpoint size of 0 - not good. In this case, we
+ * want to override the endpoint descriptor setting and use a
+ * value of 64 for wMaxPacketSize */
+ for (i = 0; i < num_endpoints; i++) {
+ dev_info(&udev->dev, "Endpoint %d MaxPacketSize %d\n", i+1,
+ interface->cur_altsetting->endpoint[i].desc.wMaxPacketSize);
+ ep_desc = &interface->cur_altsetting->endpoint[i].desc;
+ if (ep_desc->wMaxPacketSize == 0) {
+ ep_desc->wMaxPacketSize = cpu_to_le16(0x40);
+ dev_info(&udev->dev, "Overriding wMaxPacketSize on endpoint %d\n", i);
+ }
+ }
+
+ /* set max packet size based on descriptor */
+ priv->max_packet_size = ep_desc->wMaxPacketSize;
+
+ dev_info(&udev->dev, "Setting MaxPacketSize %d\n", priv->max_packet_size);
+}
+
+
/*
* ***************************************************************************
* Sysfs Attribute
@@ -1485,6 +1524,7 @@
usb_set_serial_port_data(port, priv);
ftdi_determine_type(port);
+ ftdi_set_max_packet_size(port);
read_latency_timer(port);
create_sysfs_attrs(port);
return 0;
@@ -1740,8 +1780,8 @@
if (data_offset > 0) {
/* Original sio needs control bytes too... */
transfer_size += (data_offset *
- ((count + (PKTSZ - 1 - data_offset)) /
- (PKTSZ - data_offset)));
+ ((count + (priv->max_packet_size - 1 - data_offset)) /
+ (priv->max_packet_size - data_offset)));
}
buffer = kmalloc(transfer_size, GFP_ATOMIC);
@@ -1763,7 +1803,7 @@
if (data_offset > 0) {
/* Original sio requires control byte at start of
each packet. */
- int user_pktsz = PKTSZ - data_offset;
+ int user_pktsz = priv->max_packet_size - data_offset;
int todo = count;
unsigned char *first_byte = buffer;
const unsigned char *current_position = buf;
@@ -1859,7 +1899,7 @@
data_offset = priv->write_offset;
if (data_offset > 0) {
/* Subtract the control bytes */
- countback -= (data_offset * DIV_ROUND_UP(countback, PKTSZ));
+ countback -= (data_offset * DIV_ROUND_UP(countback, priv->max_packet_size));
}
spin_lock_irqsave(&priv->tx_lock, flags);
--priv->tx_outstanding_urbs;
@@ -1961,7 +2001,7 @@
/* count data bytes, but not status bytes */
countread = urb->actual_length;
- countread -= 2 * DIV_ROUND_UP(countread, PKTSZ);
+ countread -= 2 * DIV_ROUND_UP(countread, priv->max_packet_size);
spin_lock_irqsave(&priv->rx_lock, flags);
priv->rx_bytes += countread;
spin_unlock_irqrestore(&priv->rx_lock, flags);
@@ -2034,7 +2074,7 @@
need_flip = 0;
for (packet_offset = priv->rx_processed;
- packet_offset < urb->actual_length; packet_offset += PKTSZ) {
+ packet_offset < urb->actual_length; packet_offset += priv->max_packet_size) {
int length;
/* Compare new line status to the old one, signal if different/
@@ -2049,7 +2089,7 @@
priv->prev_status = new_status;
}
- length = min_t(u32, PKTSZ, urb->actual_length-packet_offset)-2;
+ length = min_t(u32, priv->max_packet_size, urb->actual_length-packet_offset)-2;
if (length < 0) {
dev_err(&port->dev, "%s - bad packet length: %d\n",
__func__, length+2);