Hi,
Macpaul Lin <macpaul.lin@xxxxxxxxxxxx> writes:
> Nowadays some embedded systems use VCOM to transfer large log and data.
> Take LTE MODEM as an example, during the long debugging stage, large
> log and data were transfer through VCOM when doing field try or in
> operator's lab. Here we suggest slightly increase the transfer buffer
> in u_serial.c for performance improving.
>
> Signed-off-by: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx>
> ---
> Changes for v2:
> - Drop previous patch for adding flag which indicates hardware capability in
> gadget.h and in DMA engine according to Alan's suggestion. Thanks.
> - Replace requested buffer size "REQ_BUF_SIZE" instead of checking hardware
> capability.
> - Refine commit messages.
> Changes for v3:
> - Code: no change.
> Commit: Add missing change log in v2.
>
> drivers/usb/gadget/function/u_serial.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index 3cfc6e2..d7912a9 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -80,6 +80,7 @@
> #define QUEUE_SIZE 16
> #define WRITE_BUF_SIZE 8192 /* TX only */
> #define GS_CONSOLE_BUF_SIZE 8192
> +#define REQ_BUF_SIZE 4096
>
> /* console info */
> struct gs_console {
> @@ -247,7 +248,7 @@ 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, REQ_BUF_SIZE);
> if (len == 0) {
> wake_up_interruptible(&port->drain_wait);
> break;
> @@ -514,7 +515,7 @@ 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, REQ_BUF_SIZE, GFP_ATOMIC);
since this can only be applied for the next merge window, it would be
much better if you work rework how requests are used here and, as I
mentioned in the other subthread, preallocate a list of requests that
get recycled. This would allow us to allocate memory without GFP_ATOMIC.
--
balbi
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