[PATCH 3.16 135/370] usb: dwc3: ep0: add dwc3_ep0_prepare_one_trb()

[Ben Hutchings]

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Felipe Balbi <felipe.ba...@linux.intel.com>

commit 7931ec86c1b738e4e90e58c6d95e5f720d45ee56 upstream.

For now this is just a cleanup patch, no functional
changes. We will be using the new function to fix a
bug introduced long ago by commit 0416e494ce7d
("usb: dwc3: ep0: correct cache sync issue in case
of ep0_bounced") and further worsened by commit
c0bd5456a470 ("usb: dwc3: ep0: handle non maxpacket
aligned transfers > 512")

Reported-by: Janusz Dziedzic <januszx.dzied...@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.ba...@linux.intel.com>
[bwh: Backported to 3.16:
 - dwc3_ep0_start_trans() doesn't have a 'chain' parameter, so don't
   give dwc3_ep0_prepare_one_trb() this parameter
 - Also delete a debug log statement, removed earlier upstream
 - Adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/usb/dwc3/ep0.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -54,20 +54,13 @@ static const char *dwc3_ep0_state_string
        }
 }
 
-static int dwc3_ep0_start_trans(struct dwc3 *dwc, u8 epnum, dma_addr_t buf_dma,
-               u32 len, u32 type)
+static void dwc3_ep0_prepare_one_trb(struct dwc3 *dwc, u8 epnum,
+               dma_addr_t buf_dma, u32 len, u32 type)
 {
-       struct dwc3_gadget_ep_cmd_params params;
        struct dwc3_trb                 *trb;
        struct dwc3_ep                  *dep;
 
-       int                             ret;
-
        dep = dwc->eps[epnum];
-       if (dep->flags & DWC3_EP_BUSY) {
-               dev_vdbg(dwc->dev, "%s: still busy\n", dep->name);
-               return 0;
-       }
 
        trb = dwc->ep0_trb;
 
@@ -80,6 +73,20 @@ static int dwc3_ep0_start_trans(struct d
                        | DWC3_TRB_CTRL_LST
                        | DWC3_TRB_CTRL_IOC
                        | DWC3_TRB_CTRL_ISP_IMI);
+}
+
+static int dwc3_ep0_start_trans(struct dwc3 *dwc, u8 epnum, dma_addr_t buf_dma,
+               u32 len, u32 type)
+{
+       struct dwc3_gadget_ep_cmd_params params;
+       struct dwc3_ep                  *dep;
+       int                             ret;
+
+       dep = dwc->eps[epnum];
+       if (dep->flags & DWC3_EP_BUSY)
+               return 0;
+
+       dwc3_ep0_prepare_one_trb(dwc, epnum, buf_dma, len, type);
 
        memset(&params, 0, sizeof(params));
        params.param0 = upper_32_bits(dwc->ep0_trb_addr);