USB: serial drivers need to use larger bulk-in buffers
When a driver doesn't know how much data a device is going to send,
the buffer size should be at least as big as the endpoint's maxpacket
value. The serial drivers don't follow this rule; many of them
request only 256-byte bulk-in buffers. As a result, they suffer
overflow errors if a high-speed device wants to send a lot of data,
because high-speed bulk endpoints are required to have a maxpacket
size of 512.
This patch (as1450) fixes the problem by using the driver's
bulk_in_size value as a minimum, always allocating buffers no smaller
than the endpoint's maxpacket size.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Flynn Marquardt <flynn@flynnux.de>
CC: <stable@kernel.org> [after .39-rc1 is out]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index c904913..45f3b9d 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -191,7 +191,8 @@
* @id_table: pointer to a list of usb_device_id structures that define all
* of the devices this structure can support.
* @num_ports: the number of different ports this device will have.
- * @bulk_in_size: bytes to allocate for bulk-in buffer (0 = end-point size)
+ * @bulk_in_size: minimum number of bytes to allocate for bulk-in buffer
+ * (0 = end-point size)
* @bulk_out_size: bytes to allocate for bulk-out buffer (0 = end-point size)
* @calc_num_ports: pointer to a function to determine how many ports this
* device has dynamically. It will be called after the probe()