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SubjectRe: [PATCH 1/1] usb: xhci: setup packets don't need DMA mapping
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;

if (xhci->quirks & XHCI_SG_TRB_CACHE_SIZE_QUIRK) {
@@ -1389,6 +1390,9 @@ static void xhci_unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
struct xhci_hcd *xhci;
bool unmap_temp_buf = false;

+ if (usb_endpoint_xfer_control(&urb->ep->desc))
+ return;
+
xhci = hcd_to_xhci(hcd);

if (urb->num_sgs && (urb->transfer_flags & URB_DMA_MAP_SINGLE))
> Signed-off-by: Daewoong Kim <daewoong00.kim@lge.com>
> ---
> drivers/usb/core/hcd.c | 4 +++-
> drivers/usb/host/xhci.c | 1 +
> include/linux/usb.h | 4 ++++
> 3 files changed, 8 insertions(+), 1 deletion(-)
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index ad5a0f405a75..b1f9eac93f0d 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -1411,7 +1411,9 @@ 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) {
> + if (hcd->self.uses_pio_for_setup_pkt) {
> + ; /* do nothing */
> + } else if (hcd->localmem_pool) {
> ret = hcd_alloc_coherent(
> urb->dev->bus, mem_flags,
> &urb->setup_dma,
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index e86940571b4c..c263aee82dc0 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -643,6 +643,7 @@ int xhci_run(struct usb_hcd *hcd)
> */
>
> hcd->uses_new_polling = 1;
> + hcd->self.uses_pio_for_setup_pkt = 1;
> if (!usb_hcd_is_primary_hcd(hcd))
> return xhci_run_finished(xhci);
>
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 7d72c4e0713c..76600e8de414 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -430,6 +430,10 @@ struct usb_bus {
> * Does the host controller use PIO
> * for control transfers?
> */
> + u8 uses_pio_for_setup_pkt; /*
> + * Does the host controller use PIO
> + * for setup packets?
> + */
> 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? */
> --
> 2.17.1
>

--

Thanks,
Peter Chen

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