-----Original Message-----
From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-
owner@xxxxxxxxxxxxxxx] On Behalf Of Martyn Welch
Sent: Thursday, January 14, 2016 10:31
To: Konstantin Shkolnyy; johan@xxxxxxxxxx
Cc: linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH v2 1/3 RESEND] USB: serial: cp210x: New 16-bit register
access functions.
On 23/12/15 02:14, Konstantin Shkolnyy wrote:
cp210x_get_config and cp210x_set_config are cumbersome to use. This
change
introduces new register access functions for 16-bit values, instead of
the above functions.
Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@xxxxxxxxx>
---
drivers/usb/serial/cp210x.c | 155
+++++++++++++++++++++++++++++++-------------
1 file changed, 111 insertions(+), 44 deletions(-)
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index fd67958..fd7c4f4 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -422,14 +422,88 @@ static int cp210x_set_config(struct
usb_serial_port *port, u8 request,
}
/*
- * cp210x_set_config_single
- * Convenience function for calling cp210x_set_config on single data
values
- * without requiring an integer pointer
+ * Reads a variable-sized block of CP210X_ registers, identified by req.
+ * Returns data into buf in native USB byte order.
*/
-static inline int cp210x_set_config_single(struct usb_serial_port *port,
- u8 request, unsigned int data)
+static int cp210x_read_reg_block(struct usb_serial_port *port, u8 req,
+ void *buf, int bufsize)
{
- return cp210x_set_config(port, request, &data, 2);
+ struct usb_serial *serial = port->serial;
+ struct cp210x_port_private *port_priv =
usb_get_serial_port_data(port);
+ void *dmabuf;
+ int result;
+
+ dmabuf = kmalloc(bufsize, GFP_KERNEL);
+ if (!dmabuf) {
+ /*
+ * FIXME Some callers don't bother to check for error,
+ * at least give them consistent junk until they are fixed
+ */
+ memset(buf, 0, bufsize);
+ return -ENOMEM;
+ }
+
+ result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev,
0),
+ req, REQTYPE_INTERFACE_TO_HOST, 0,
+ port_priv->bInterfaceNumber, dmabuf, bufsize,
+ USB_CTRL_SET_TIMEOUT);
+ if (result == bufsize) {
+ memcpy(buf, dmabuf, bufsize);
+ result = 0;
I could be wrong, but isn't dmabuf a little-endian stream (hence the
byte order swapping in the existing set and get functions). Won't this
break on big endian systems due to the lack of byte swapping?
