From: Gadiyar, Anand
>
> The Inventra DMA engine used with the MUSB controller in many
> SoCs cannot use DMA for control transfers on EP0, but can use
> DMA for all other transfers.
>
> The USB core maps urbs for DMA if hcd->self.uses_dma is true.
> (hcd->self.uses_dma is true for MUSB as well).
>
> Split the uses_dma flag into two - one that says if the
> controller needs to use PIO for control transfers, and
> another which says if the controller uses DMA (for all
> other transfers).
>
> Also, populate this flag for all MUSB by default.
>
> (Tested on OMAP3 and OMAP4 boards, with EHCI and MUSB HCDs
> simultaneously in use).
>
> Signed-off-by: Anand Gadiyar <gadiyar@xxxxxx>
> Cc: Oliver Neukum <oliver@xxxxxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Cc: Praveena NADAHALLY <praveen.nadahally@xxxxxxxxxxxxxx>
> Cc: Felipe Balbi <felipe.balbi@xxxxxxxxx>
> Cc: Ajay Kumar Gupta <ajay.gupta@xxxxxx>
Explicitly CC'ing Santosh and Maulik who originally reported
the issue and came up with the initial patch.
> ---
> v2:
> - Updated patch addressing Alan's comments
> - Remove RFC tag
> - Cc Felipe and Ajay for the MUSB parts
>
> - I've populated the uses_pio_for_control flag for all
> MUSB HCDs. Even though some DMA engines used with MUSB may
> be able to carry out control transfers using DMA, there may
> not be much to be gained. If someone disagrees, I'll respin
> the patch to populate this flag for the Inventra engine alone.
>
> drivers/usb/core/hcd.c | 4 +++-
> drivers/usb/musb/musb_core.c | 3 +++
> drivers/usb/musb/musb_gadget.c | 4 ++++
> include/linux/usb.h | 4 ++++
> 4 files changed, 14 insertions(+), 1 deletion(-)
>
> Index: kernel-omap4-base/drivers/usb/core/hcd.c
> ===================================================================
> --- kernel-omap4-base.orig/drivers/usb/core/hcd.c 2010-08-04 14:57:04.129928076 +0530
> +++ kernel-omap4-base/drivers/usb/core/hcd.c 2010-08-04 15:02:18.577938877 +0530
> @@ -1321,7 +1321,9 @@
> */
>
> if (usb_endpoint_xfer_control(&urb->ep->desc)) {
> - if (hcd->self.uses_dma) {
> + if (hcd->self.uses_pio_for_control) {
> + urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
> + } else if (hcd->self.uses_dma) {
> urb->setup_dma = dma_map_single(
> hcd->self.controller,
> urb->setup_packet,
> Index: kernel-omap4-base/include/linux/usb.h
> ===================================================================
> --- kernel-omap4-base.orig/include/linux/usb.h 2010-08-04 14:57:04.109948812 +0530
> +++ kernel-omap4-base/include/linux/usb.h 2010-08-04 14:58:20.817938610 +0530
> @@ -311,6 +311,10 @@
> int busnum; /* Bus number (in order of reg) */
> const char *bus_name; /* stable id (PCI slot_name etc) */
> u8 uses_dma; /* Does the host controller use DMA? */
> + 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? */
> Index: kernel-omap4-base/drivers/usb/musb/musb_core.c
> ===================================================================
> --- kernel-omap4-base.orig/drivers/usb/musb/musb_core.c 2010-08-04 14:57:04.121928264 +0530
> +++ kernel-omap4-base/drivers/usb/musb/musb_core.c 2010-08-04 14:57:26.642178087 +0530
> @@ -2107,12 +2107,15 @@
> * Otherwise, wait till the gadget driver hooks up.
> */
> if (!is_otg_enabled(musb) && is_host_enabled(musb)) {
> + struct usb_hcd *hcd = musb_to_hcd(musb);
> +
> MUSB_HST_MODE(musb);
> musb->xceiv->default_a = 1;
> musb->xceiv->state = OTG_STATE_A_IDLE;
>
> status = usb_add_hcd(musb_to_hcd(musb), -1, 0);
>
> + hcd->self.uses_pio_for_control = 1;
> DBG(1, "%s mode, status %d, devctl %02x %c\n",
> "HOST", status,
> musb_readb(musb->mregs, MUSB_DEVCTL),
> Index: kernel-omap4-base/drivers/usb/musb/musb_gadget.c
> ===================================================================
> --- kernel-omap4-base.orig/drivers/usb/musb/musb_gadget.c 2010-08-04 14:57:04.113928462 +0530
> +++ kernel-omap4-base/drivers/usb/musb/musb_gadget.c 2010-08-04 14:57:26.642178087 +0530
> @@ -1763,6 +1763,8 @@
> spin_unlock_irqrestore(&musb->lock, flags);
>
> if (is_otg_enabled(musb)) {
> + struct usb_hcd *hcd = musb_to_hcd(musb);
> +
> DBG(3, "OTG startup...\n");
>
> /* REVISIT: funcall to other code, which also
> @@ -1832,6 +1834,8 @@
> musb->gadget_driver = NULL;
> musb->g.dev.driver = NULL;
> spin_unlock_irqrestore(&musb->lock, flags);
> + } else {
> + hcd->self.uses_pio_for_control = 1;
> }
> }
> }
>
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