drivers: udc_dwc2: Allow not-multiple-of-4 mps in DMA mode (debc7446) · Commits · Wenxi XU / zephyr

Remove the early max packet size check on endpoint activation, because there are valid use cases where the max packet size is not multiple of 4 and the stack won't perform multi-transaction transfers. Example use case is UAC2 explicit feedback endpoint that has Max Packet Size equal 3 when device is operating at Full-Speed. Signed-off-by:

Tomasz Moń <tomasz.mon@nordicsemi.no>

drivers/usb/udc/udc_dwc2.c

+0 −17

Original line number	Diff line number	Diff line
		@@ -1491,23 +1491,6 @@ static int udc_dwc2_ep_activate(const struct device *dev,
		dxepctl_reg = (mem_addr_t)&base->in_ep[ep_idx].diepctl;
		}

		if (priv->bufferdma && (udc_mps_ep_size(cfg) % 4)) {
		/* TODO: In Buffer DMA mode, DMA will insert padding bytes in
		* between packets if endpoint Max Packet Size is not multiple
		* of 4 (DWORD) and single transfer spans across multiple
		* packets.
		*
		* In order to support such Max Packet Sizes, the driver would
		* have to remove the padding in between the packets. Besides
		* just driver shuffling the data, the buffers would have to be
		* large enough to temporarily hold the paddings.
		*
		* For the time being just error out early.
		*/
		LOG_ERR("Driver requires MPS to be multiple of 4");
		return -EINVAL;
		}

		dxepctl = sys_read32(dxepctl_reg);
		/* Set max packet size */
		dxepctl &= ~USB_DWC2_DEPCTL_MPS_MASK;

Admin message