Hi,
Macpaul Lin <macpaul.lin@xxxxxxxxxxxx> writes:
> If the hardware (like DMA engine) could support large usb request exceeds
> maximum packet size, use larger buffer when performing Rx/Tx could reduce
> request numbers and improve performance.
>
> Signed-off-by: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx>
> ---
> drivers/usb/gadget/function/u_serial.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index 3cfc6e2..cdcc070 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -80,6 +80,8 @@
> #define QUEUE_SIZE 16
> #define WRITE_BUF_SIZE 8192 /* TX only */
> #define GS_CONSOLE_BUF_SIZE 8192
> +/* for hardware can do more than max packet */
> +#define REQ_BUF_SIZE 4096
>
> /* console info */
> struct gs_console {
> @@ -247,7 +249,8 @@ static int gs_start_tx(struct gs_port *port)
> break;
>
> req = list_entry(pool->next, struct usb_request, list);
> - len = gs_send_packet(port, req->buf, in->maxpacket);
> + len = gs_send_packet(port, req->buf, in->can_exceed_maxp ?
> + REQ_BUF_SIZE : in->maxpacket);
just do this unconditionally.
> if (len == 0) {
> wake_up_interruptible(&port->drain_wait);
> break;
> @@ -514,7 +517,9 @@ static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
> * be as speedy as we might otherwise be.
> */
> for (i = 0; i < n; i++) {
> - req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
> + req = gs_alloc_req(ep, ep->can_exceed_maxp ?
> + REQ_BUF_SIZE : ep->maxpacket,
> + GFP_ATOMIC);
allocating 4kiB in atomic isn't very good. A better idea would be to
preallocate a list of requests and recycle them, rather than allocating
every time you need to do a transfer
--
balbi
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