On 20-06-29 23:18:45, Ruslan Bilovol wrote:
> UDC hardware may have endpoints with different maxpacket
> size. Current endpoint matching code takes first matching
> endpoint from the list.
>
> It's always possible that gadget allocates endpoints for
> small transfers (maxpacket size) first, then larger ones.
> That works fine if all matching UDC endpoints have same
> maxpacket size or are big enough to serve that allocation.
>
> However, some UDCs have first endpoints in the list with
> bigger maxpacket size, whereas last endpoints are much
> smaller. In this case endpoint allocation will fail for
> the gadget (which allocates smaller endpoints first) on
> final endpoint allocations.
>
> To make endpoint allocation fair, pick up smallest
> matching endpoints first, leaving bigger ones for
> heavier applications.
>
> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx>
> ---
>
> v2: rebased onto latest balbi/next branch
>
> drivers/usb/gadget/epautoconf.c | 23 ++++++++++++++++++-----
> 1 file changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
> index 1eb4fa2e623f..6c453b5d87bb 100644
> --- a/drivers/usb/gadget/epautoconf.c
> +++ b/drivers/usb/gadget/epautoconf.c
> @@ -66,7 +66,7 @@ struct usb_ep *usb_ep_autoconfig_ss(
> struct usb_ss_ep_comp_descriptor *ep_comp
> )
> {
> - struct usb_ep *ep;
> + struct usb_ep *ep, *ep_min = NULL;
>
> if (gadget->ops->match_ep) {
> ep = gadget->ops->match_ep(gadget, desc, ep_comp);
> @@ -74,14 +74,27 @@ struct usb_ep *usb_ep_autoconfig_ss(
> goto found_ep;
> }
>
> - /* Second, look at endpoints until an unclaimed one looks usable */
> + /*
> + * Second, look at endpoints until an unclaimed one looks usable.
> + * Try to find one with smallest maxpacket limit, leaving larger
> + * endpoints for heavier applications
> + */
> list_for_each_entry (ep, &gadget->ep_list, ep_list) {
> - if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
> - goto found_ep;
> + if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp)) {
> + if (desc->wMaxPacketSize == 0)
> + goto found_ep;
Why you do special handling for this? You still could give the smallest
maxpacket_limit EP for it, right?
Peter
> + else if (!ep_min)
> + ep_min = ep;
> + else if (ep->maxpacket_limit < ep_min->maxpacket_limit)
> + ep_min = ep;
> + }
> }
>
> /* Fail */
> - return NULL;
> + if (!ep_min)
> + return NULL;
> +
> + ep = ep_min;
> found_ep:
>
> /*
> --
> 2.17.1
>
--
Thanks,
Peter Chen
