usb: dma bounce buffer support

usb: dma bounce buffer support V4

This patch adds dma bounce buffer support to the usb core. These buffers
can be enabled with the HCD_LOCAL_MEM flag, and they make sure that all data
passed to the host controller is allocated using dma_alloc_coherent().

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c
index 28d4972f7ad5..acd9f00a0b76 100644
--- a/drivers/usb/core/buffer.c
+++ b/drivers/usb/core/buffer.c
@@ -53,7 +53,8 @@ int hcd_buffer_create(struct usb_hcd *hcd)
         char            name[16];
         int             i, size;
 
-        if (!hcd->self.controller->dma_mask)
+        if (!hcd->self.controller->dma_mask &&
+            !(hcd->driver->flags & HCD_LOCAL_MEM))
                 return 0;
 
         for (i = 0; i < HCD_BUFFER_POOLS; i++) { 
@@ -107,7 +108,8 @@ void *hcd_buffer_alloc(
         int                     i;
 
         /* some USB hosts just use PIO */
-        if (!bus->controller->dma_mask) {
+        if (!bus->controller->dma_mask &&
+            !(hcd->driver->flags & HCD_LOCAL_MEM)) {
                 *dma = ~(dma_addr_t) 0;
                 return kmalloc(size, mem_flags);
         }
@@ -132,7 +134,8 @@ void hcd_buffer_free(
         if (!addr)
                 return;
 
-        if (!bus->controller->dma_mask) {
+        if (!bus->controller->dma_mask &&
+            !(hcd->driver->flags & HCD_LOCAL_MEM)) {
                 kfree(addr);
                 return;
         }