On Mon, Oct 07, 2024 at 03:02:34PM +0300, Roger Quadros wrote:
Hello Roger,
On 07/10/2024 13:42, Siddharth Vadapalli wrote:
The function cdns3_ep_config() calculates the maximum packet size based on the Endpoint Type and the Gadget Speed and stores it in the variable "max_packet_size". This value is then programmed in the USB Controller for the corresponding Endpoint. This may result in a mismatch between the maximum packet size programmed in the USB controller and the maximum packet size seen by the UDC Core via "maxpacket" member of "struct usb_ep". Additionally, since TD_SIZE is calculated in cdns3_ep_run_transfer() on the basis of the maximum packet size stored in the "maxpacket" member of "struct usb_ep", it may lead to an incorrect value of TD_SIZE when compared with what the USB controller actually expects (max_packet_size).
[...]
diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c index ac7e469469..b0b08768d9 100644 --- a/drivers/usb/cdns3/gadget.c +++ b/drivers/usb/cdns3/gadget.c @@ -1637,6 +1637,14 @@ void cdns3_ep_config(struct cdns3_endpoint *priv_ep) else priv_ep->trb_burst_size = 16;
- /*
* The Endpoint is configured to handle a maximum packet size of* max_packet_size. Hence, set priv_ep->endpoint.maxpacket to* max_packet_size. This is necessary to ensure that the TD_SIZE* is calculated correctly in cdns3_ep_run_transfer().*/- usb_ep_set_maxpacket_limit(&priv_ep->endpoint, max_packet_size);
from include/linux/usb/gadget.h
- struct usb_ep - device side representation of USB endpoint
...
- @maxpacket:The maximum packet size used on this endpoint. The initial
value can sometimes be reduced (hardware allowing), according tothe endpoint descriptor used to configure the endpoint.- @maxpacket_limit:The maximum packet size value which can be handled by this
endpoint. It's set once by UDC driver when endpoint is initialized, andshould not be changed. Should not be confused with maxpacket.What you want to change is ep->maxpacket and not ep->maxpacket_limit as that is fixed for a particular UDC.
how about? priv-ep->endpoint.maxpacket = max_packet_size;
Yes, this is accurate. I will post the v2 patch with this change. Thank you for reviewing the patch.
Regards, Siddharth.