usb: dwc3: gadget: allocate 3 packets for bulk and isoc endpoints

Those transfer types are generally high bandwidth, so we
want to optimize transfers with those endpoints.

For that, databook suggests allocating 3 * wMaxPacketSize
of FIFO. Let's do that.

Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 1f64e7c..c30ab6d 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -172,6 +172,7 @@ int dwc3_gadget_resize_tx_fifos(struct dwc3 *dwc)
        for (num = 0; num < DWC3_ENDPOINTS_NUM; num++) {
                struct dwc3_ep  *dep = dwc->eps[num];
                int             fifo_number = dep->number >> 1;
+               int             mult = 1;
                int             tmp;
 
                if (!(dep->number & 1))
@@ -180,11 +181,26 @@ int dwc3_gadget_resize_tx_fifos(struct dwc3 *dwc)
                if (!(dep->flags & DWC3_EP_ENABLED))
                        continue;
 
-               tmp = dep->endpoint.maxpacket;
-               tmp += mdwidth;
+               if (usb_endpoint_xfer_bulk(dep->desc)
+                               || usb_endpoint_xfer_isoc(dep->desc))
+                       mult = 3;
+
+               /*
+                * REVISIT: the following assumes we will always have enough
+                * space available on the FIFO RAM for all possible use cases.
+                * Make sure that's true somehow and change FIFO allocation
+                * accordingly.
+                *
+                * If we have Bulk or Isochronous endpoints, we want
+                * them to be able to be very, very fast. So we're giving
+                * those endpoints a fifo_size which is enough for 3 full
+                * packets
+                */
+               tmp = mult * (dep->endpoint.maxpacket + mdwidth);
                tmp += mdwidth;
 
                fifo_size = DIV_ROUND_UP(tmp, mdwidth);
+
                fifo_size |= (last_fifo_depth << 16);
 
                dev_vdbg(dwc->dev, "%s: Fifo Addr %04x Size %d\n",