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usb: gadget: Add support for DMA mapping optimization of request buffers

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In order to improve performance, this patch enabled mapping of USB request
buffers in advance, before queueing them to the HW. This can be used when
there is a pool or pre-mapped request buffers so we don't need to map it
again every time the request gets queued.

Change-Id: Ic3a6db749343ef1345e0816210517755aee055b3
Signed-off-by: Danny Segal <dsegal@codeaurora.org>
Signed-off-by: Mayank Rana <mrana@codeaurora.org>
This commit is contained in:
Danny Segal 2014-04-08 10:49:55 +03:00 • committed by David Keitel
parent b0129f471b
commit 060b80f220
2 changed files with 14 additions and 2 deletions
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10
drivers/usb/gadget/udc/udc-core.c
View file

@ -76,7 +76,7 @@ int usb_gadget_map_request(struct usb_gadget *gadget,
}
req->num_mapped_sgs = mapped;
} else {
} else if (!req->dma_pre_mapped) {
req->dma = dma_map_single(dev, req->buf, req->length,
is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
@ -101,9 +101,15 @@ void usb_gadget_unmap_request(struct usb_gadget *gadget,
is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
req->num_mapped_sgs = 0;
} else {
} else if (!req->dma_pre_mapped && req->dma != DMA_ERROR_CODE) {
/*
* If the DMA address has not been mapped by a higher layer,
* then unmap it here. Otherwise, the DMA address will be
* unmapped by the upper layer (where the request was queued).
*/
dma_unmap_single(gadget->dev.parent, req->dma, req->length,
is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
req->dma = DMA_ERROR_CODE;
}
}
EXPORT_SYMBOL_GPL(usb_gadget_unmap_request);

6
include/linux/usb/gadget.h
View file

@ -118,6 +118,11 @@ struct gsi_channel_info {
* 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_pre_mapped: Tells the USB core driver whether this request should be
* DMA-mapped before it is queued to the USB HW. When set to true, it means
* that the request has already been mapped in advance and therefore the
* USB core driver does NOT need to do DMA-mapping when the request is
* queued to the USB HW.
* @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.
@ -174,6 +179,7 @@ struct usb_request {
unsigned no_interrupt:1;
unsigned zero:1;
unsigned short_not_ok:1;
unsigned dma_pre_mapped:1;
void (*complete)(struct usb_ep *ep,
struct usb_request *req);