Re: [PATCH V6 03/10] USB: f81232: implement RX bulk-in ep

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Feb 16, 2015 at 03:57:55PM +0800, Peter Hung wrote:
> The F81232 bulk-in is RX data + LSR channel, data format is
> [LSR+Data][LSR+Data]..... , We had reimplemented in this patch.
> 
> Signed-off-by: Peter Hung <hpeter+linux_kernel@gmail.com>
> ---
>  drivers/usb/serial/f81232.c | 68 +++++++++++++++++++++++----------------------
>  1 file changed, 35 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
> index ec4609d..9ea498a 100644
> --- a/drivers/usb/serial/f81232.c
> +++ b/drivers/usb/serial/f81232.c
> @@ -185,44 +185,46 @@ exit:
>  static void f81232_process_read_urb(struct urb *urb)
>  {
>  	struct usb_serial_port *port = urb->context;
> -	struct f81232_private *priv = usb_get_serial_port_data(port);
>  	unsigned char *data = urb->transfer_buffer;
> -	char tty_flag = TTY_NORMAL;
> -	unsigned long flags;
> -	u8 line_status;
> +	char tty_flag;
>  	int i;
>  
> -	/* update line status */
> -	spin_lock_irqsave(&priv->lock, flags);
> -	line_status = priv->modem_status;
> -	priv->modem_status &= ~UART_STATE_TRANSIENT_MASK;
> -	spin_unlock_irqrestore(&priv->lock, flags);
> -
> -	if (!urb->actual_length)
> +	if (urb->actual_length < 2)
>  		return;
>  
> -	/* break takes precedence over parity, */
> -	/* which takes precedence over framing errors */
> -	if (line_status & UART_BREAK_ERROR)
> -		tty_flag = TTY_BREAK;
> -	else if (line_status & UART_PARITY_ERROR)
> -		tty_flag = TTY_PARITY;
> -	else if (line_status & UART_FRAME_ERROR)
> -		tty_flag = TTY_FRAME;
> -	dev_dbg(&port->dev, "%s - tty_flag = %d\n", __func__, tty_flag);
> -
> -	/* overrun is special, not associated with a char */
> -	if (line_status & UART_OVERRUN_ERROR)
> -		tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
> -
> -	if (port->port.console && port->sysrq) {
> -		for (i = 0; i < urb->actual_length; ++i)
> -			if (!usb_serial_handle_sysrq_char(port, data[i]))
> -				tty_insert_flip_char(&port->port, data[i],
> -						tty_flag);
> -	} else {
> -		tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag,
> -							urb->actual_length);
> +	/* bulk-in data: [LSR(1Byte)+DATA(1Byte)][LSR(1Byte)+DATA(1Byte)]... */
> +
> +	for (i = 0 ; i < urb->actual_length ; i += 2) {
> +		tty_flag = TTY_NORMAL;
> +
> +		if (unlikely(data[i+0] & UART_LSR_BRK_ERROR_BITS)) {

Never use unlikely() unless you can prove that it actually matters if
you use it.  Hint, it's almost impossible to prove, so don't use it, the
compiler and processor look-ahead is almost smarter than we are.

thanks,

greg k-h