usb: dwc2: gadget: Transfer length limit checking for DDMA

Add dwc2_gadget_get_chain_limit() function and its call in transfer
start routine to correctly estimate one go on transfer size if
descriptor DMA mode is selected.

Signed-off-by: Vahram Aharonyan <vahrama@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 729bc02d0f6e7a9cd77f7139eba5a27e23f45a49..4c1098f84431c324f4bfc249cc50b427aa188c7e 100644 (file)
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -601,6 +601,32 @@ static u32 dwc2_hsotg_read_frameno(struct dwc2_hsotg *hsotg)
        return dsts;
 }
 
+/**
+ * dwc2_gadget_get_chain_limit - get the maximum data payload value of the
+ * DMA descriptor chain prepared for specific endpoint
+ * @hs_ep: The endpoint
+ *
+ * Return the maximum data that can be queued in one go on a given endpoint
+ * depending on its descriptor chain capacity so that transfers that
+ * are too long can be split.
+ */
+static unsigned int dwc2_gadget_get_chain_limit(struct dwc2_hsotg_ep *hs_ep)
+{
+       int is_isoc = hs_ep->isochronous;
+       unsigned int maxsize;
+
+       if (is_isoc)
+               maxsize = hs_ep->dir_in ? DEV_DMA_ISOC_TX_NBYTES_LIMIT :
+                                          DEV_DMA_ISOC_RX_NBYTES_LIMIT;
+       else
+               maxsize = DEV_DMA_NBYTES_LIMIT;
+
+       /* Above size of one descriptor was chosen, multiple it */
+       maxsize *= MAX_DMA_DESC_NUM_GENERIC;
+
+       return maxsize;
+}
+
 /**
  * dwc2_hsotg_start_req - start a USB request from an endpoint's queue
  * @hsotg: The controller state.
@@ -659,7 +685,11 @@ static void dwc2_hsotg_start_req(struct dwc2_hsotg *hsotg,
        dev_dbg(hsotg->dev, "ureq->length:%d ureq->actual:%d\n",
                ureq->length, ureq->actual);
 
-       maxreq = get_ep_limit(hs_ep);
+       if (!using_desc_dma(hsotg))
+               maxreq = get_ep_limit(hs_ep);
+       else
+               maxreq = dwc2_gadget_get_chain_limit(hs_ep);
+
        if (length > maxreq) {
                int round = maxreq % hs_ep->ep.maxpacket;