usb: musb: do not use dma for control transfers

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: Maulik Mankad <x0082077@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Praveena NADAHALLY <praveen.nadahally@stericsson.com>
Cc: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

4 files changed, 13 insertions, 0 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 61800f77dac8..ced846ac4141 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1330,6 +1330,8 @@ static int 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->self.uses_dma) {
                         urb->setup_dma = dma_map_single(
                                         hcd->self.controller,
diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index e6669fc3b804..99beebce8550 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -2116,12 +2116,15 @@ bad_config:
          * 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),
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index c8de0e123f2c..9d6ade82b9f2 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -1833,6 +1833,8 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver,
                 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
@@ -1847,6 +1849,8 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver,
                                 musb->gadget_driver = NULL;
                                 musb->g.dev.driver = NULL;
                                 spin_unlock_irqrestore(&musb->lock, flags);
+                        } else {
+                                hcd->self.uses_pio_for_control = 1;
                         }
                 }
         }
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 24300d8a1bc1..a28eb2592577 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -313,6 +313,10 @@ struct usb_bus {
         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? */