[PATCH v5 3/6] usb: gadget: Support already-mapped DMA SGs

Paul Cercueil
2024-01-19T14:14:37Z

Add a new 'sg_was_mapped' field to the struct usb_request. This field
can be used to indicate that the scatterlist associated to the USB
transfer has already been mapped into the DMA space, and it does not
have to be done internally.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
drivers/usb/gadget/udc/core.c | 7 ++++++-
include/linux/usb/gadget.h | 2 ++
2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index d59f94464b87..9d4150124fdb 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -903,6 +903,11 @@ int usb_gadget_map_request_by_dev(struct device *dev,
if (req->length == 0)
return 0;

+ if (req->sg_was_mapped) {
+ req->num_mapped_sgs = req->num_sgs;
+ return 0;
+ }
+
if (req->num_sgs) {
int mapped;

@@ -948,7 +953,7 @@ EXPORT_SYMBOL_GPL(usb_gadget_map_request);
void usb_gadget_unmap_request_by_dev(struct device *dev,
struct usb_request *req, int is_in)
{
- if (req->length == 0)
+ if (req->length == 0 || req->sg_was_mapped)
return;

if (req->num_mapped_sgs) {
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index a771ccc038ac..c529e4e06997 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -52,6 +52,7 @@ struct usb_ep;
* @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)
+ * @sg_was_mapped: Set if the scatterlist has been mapped before the request
* @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.
@@ -111,6 +112,7 @@ struct usb_request {
unsigned zero:1;
unsigned short_not_ok:1;
unsigned dma_mapped:1;
+ unsigned sg_was_mapped:1;

void (*complete)(struct usb_ep *ep,
struct usb_request *req);
--
2.43.0