Peter Chen, thanks for your comments.
On Fri, 15 Jan 2021 08:32:51 +0800, Peter Chen wrote:
> On 21-01-14 13:00:21, Alan Stern wrote:
> > On Thu, Jan 14, 2021 at 01:04:02PM +0800, Peter Chen wrote:
> > > On 21-01-14 11:59:07, Daewoong Kim wrote:
> > > > DMA mapping of urb->setup_packet is not necessary for xHCI host
> > > > controllers. The xHCI specification says that Setup Stage TRB includes
> > > > whole Setup Data; therefore, urb->setup_dma will not be used in the xhci
> > > > HCD code.
> > > >
> > >
> > > How about bypass map/unmap operation for xHCI control transfer directly?
> > >
> > > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > > index 91ab81c3fc79..0a0ab14b7638 100644
> > > --- a/drivers/usb/host/xhci.c
> > > +++ b/drivers/usb/host/xhci.c
> > > @@ -1374,7 +1374,8 @@ static int xhci_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
> > >
> > > xhci = hcd_to_xhci(hcd);
> > >
> > > - if (xhci_urb_suitable_for_idt(urb))
> > > + if (xhci_urb_suitable_for_idt(urb) ||
> > > + (usb_endpoint_xfer_control(&urb->ep->desc)))
> > > return 0;
> >
> > Would this affect the map/unmap operations for the DATA packets in a
> > control transfer, along with the SETUP packet?
> >
>
> Oh, you are right, Alan. We do need map/unmap operation for DATA
> packet in control transfer.
Is it possible to bypass map/unmap operations for MUSB devices' control transfer directly?
If possible, the uses_pio_for_control field in struct usb_bus could be removed.
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index ad5a0f405a75..54061764ffda 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1409,8 +1409,6 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
*/
if (usb_endpoint_xfer_control(&urb->ep->desc)) {
- if (hcd->self.uses_pio_for_control)
- return ret;
if (hcd->localmem_pool) {
ret = hcd_alloc_coherent(
urb->dev->bus, mem_flags,
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 30c5e7de0761..6eaff08cd1e4 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -2624,6 +2624,8 @@ static int musb_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
struct musb *musb = hcd_to_musb(hcd);
int ret;
+ if (usb_endpoint_xfer_control(&urb->ep->desc))
+ return 0;
/*
* The DMA engine in RTL1.8 and above cannot handle
* DMA addresses that are not aligned to a 4 byte boundary.
@@ -2700,7 +2702,6 @@ int musb_host_alloc(struct musb *musb)
return -EINVAL;
*musb->hcd->hcd_priv = (unsigned long) musb;
- musb->hcd->self.uses_pio_for_control = 1;
musb->hcd->uses_new_polling = 1;
musb->hcd->has_tt = 1;
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 7d72c4e0713c..f4b7d529f2eb 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -426,10 +426,6 @@ struct usb_bus {
struct device *sysdev; /* as seen from firmware or bus */
int busnum; /* Bus number (in order of reg) */
const char *bus_name; /* stable id (PCI slot_name etc) */
- u8 uses_pio_for_control; /*
- * Does the host controller use PIO
- * for control transfers?
- */
u8 otg_port; /* 0, or number of OTG/HNP port */
unsigned is_b_host:1; /* true during some HNP roleswitches */
unsigned b_hnp_enable:1; /* OTG: did A-Host enable HNP? */
--
With Best Regards,
Daewoong Kim
