usb: gadget: core: unmap request from DMA only if previously mapped

In the SG case this is already handled since a non-zero
request->num_mapped_sgs is a clear indicator that dma_map_sg()
had been called. While it would be nice to do the same for the
singly mapped case by simply checking for non-zero request->dma,
it's conceivable that 0 is a valid dma_addr_t handle. Hence add
a flag 'dma_mapped' to struct usb_request and use this to
determine the need to call dma_unmap_single(). Otherwise, if a
request is not DMA mapped then the result of calling
usb_request_unmap_request() would safely be a no-op.

Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index e6f04ee..c1cef6a 100644 (file)
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -812,6 +812,8 @@ int usb_gadget_map_request_by_dev(struct device *dev,
                        dev_err(dev, "failed to map buffer\n");
                        return -EFAULT;
                }
+
+               req->dma_mapped = 1;
        }
 
        return 0;
@@ -836,9 +838,10 @@ void usb_gadget_unmap_request_by_dev(struct device *dev,
                                is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 
                req->num_mapped_sgs = 0;
-       } else {
+       } else if (req->dma_mapped) {
                dma_unmap_single(dev, req->dma, req->length,
                                is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+               req->dma_mapped = 0;
        }
 }
 EXPORT_SYMBOL_GPL(usb_gadget_unmap_request_by_dev);

diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 1a4a4ba..21468a7 100644 (file)
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -48,6 +48,7 @@ struct usb_ep;
  *     by adding a zero length packet as needed;
  * @short_not_ok: When reading data, makes short packets be
  *     treated as errors (queue stops advancing till cleanup).
+ * @dma_mapped: Indicates if request has been mapped to DMA (internal)
  * @complete: Function called when request completes, so this request and
  *     its buffer may be re-used.  The function will always be called with
  *     interrupts disabled, and it must not sleep.
@@ -103,6 +104,7 @@ struct usb_request {
        unsigned                no_interrupt:1;
        unsigned                zero:1;
        unsigned                short_not_ok:1;
+       unsigned                dma_mapped:1;
 
        void                    (*complete)(struct usb_ep *ep,
                                        struct usb_request *req);