[RESEND PATCH 02/16] serial: usbtty: Send urb data in correct order

[Lukasz Majewski]

On Fri,  5 Feb 2021 20:11:58 +0100
Pali Rohár <pali at kernel.org> wrote:

> Function next_urb() selects the last urb data buffer from linked list
> to which next data from usbtty puts should be appended.
> 
> But to check if TX data still exists it is needed to look at the
> first urb data buffer from linked list. So check for endpoint->tx_urb
> (first from the linked list) instead of current_urb (the last from
> the linked list).
> 
> Successful call to udc_endpoint_write() may invalidate active urb and
> allocate new in queue which invalidate pointer returned by next_urb()
> function.
> 
> So call next_urb() prior putting data into urb buffer and call it
> every time after using udc_endpoint_write() function to prevent
> sending data from usbtty puts in incorrect order.
> 
> This patch fixes issue that usbtty code does not transmit data when
> they are waiting in the tx queue.

Reviewed-by: Lukasz Majewski <lukma at denx.de>

> 
> Signed-off-by: Pali Rohár <pali at kernel.org>
> ---
>  drivers/serial/usbtty.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/serial/usbtty.c b/drivers/serial/usbtty.c
> index 02f8edf200..4f4eb02de0 100644
> --- a/drivers/serial/usbtty.c
> +++ b/drivers/serial/usbtty.c
> @@ -849,17 +849,9 @@ static int write_buffer (circbuf_t * buf)
>  			&endpoint_instance[tx_endpoint];
>  	struct urb *current_urb = NULL;
>  
> -	current_urb = next_urb (device_instance, endpoint);
> -
> -	if (!current_urb) {
> -		TTYERR ("current_urb is NULL, buf->size %d\n",
> -		buf->size);
> -		return 0;
> -	}
> -
>  	/* TX data still exists - send it now
>  	 */
> -	if(endpoint->sent < current_urb->actual_length){
> +	if(endpoint->sent < endpoint->tx_urb->actual_length){
>  		if(udc_endpoint_write (endpoint)){
>  			/* Write pre-empted by RX */
>  			return -1;
> @@ -878,6 +870,8 @@ static int write_buffer (circbuf_t * buf)
>  		 */
>  		while (buf->size > 0) {
>  
> +			current_urb = next_urb (device_instance,
> endpoint); +
>  			dest = (char*)current_urb->buffer +
>  				current_urb->actual_length;
>  




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de
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