Hi Frank,
Le vendredi 19 janvier 2024 à 16:49 -0500, Frank Li a écrit :
> On Wed, Jan 17, 2024 at 01:26:43PM +0100, Paul Cercueil wrote:
> > 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@xxxxxxxxxxxxxxx>
> > ---
> > 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;
>
> why not use dma_mapped direclty?
Because of the unmap case. We want to know whether we should unmap or
not.
>
> Frank
Cheers,
-Paul
>
> >
> > void (*complete)(struct usb_ep *ep,
> > struct usb_request *req);
> > --
> > 2.43.0
> >
