USB: pl2303: increase the bulk-out buffer size to 256 byte

Increase the bulk-out buffer size from 64 to 256 byte.

This gives a significant increase in throughput already at 1Mbaud as well
as lowered CPU usage. The buffer is big enough to keep up also at 3Mbaud
(128b would not suffice).

        64b         256b
921k:   640 KB/s    870 KB/s
3M:     640 KB/s    2520 KB/s

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index b10b0efe3e0606a64e5f37ded3ce848d8386c4ee..03fe472fee3215456db80a38971b88880371ca13 100644 (file)
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -1170,6 +1170,7 @@ static struct usb_serial_driver pl2303_device = {
        .id_table =             id_table,
        .usb_driver =           &pl2303_driver,
        .num_ports =            1,
+       .bulk_out_size =        256,
        .open =                 pl2303_open,
        .close =                pl2303_close,
        .dtr_rts =              pl2303_dtr_rts,