[PATCH 2/2] usb: host: xhci: using dma pool for scratchpad buffer

[Peter Chen <peter.chen@xxxxxxx>]

According to xHCI ch4.20 Scratchpad Buffers
	A Scratchpad Buffer is a PAGESIZE block of system memory
       	located on a PAGESIZE boundary
	...
	Software clears the Scratchpad Buffer to ‘0’

So, we need to use dma pool for PAGESIZE boundary buffer, and zeroed
its region using dma_pool_zalloc.

Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
---
 drivers/usb/host/xhci-mem.c | 21 +++++++++++++++------
 drivers/usb/host/xhci.h     |  1 +
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 22a03b7..56aa0a6 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1710,12 +1710,18 @@ static int scratchpad_alloc(struct xhci_hcd *xhci, gfp_t flags)
 		goto fail_sp3;
 
 	xhci->dcbaa->dev_context_ptrs[0] = cpu_to_le64(xhci->scratchpad->sp_dma);
+
+	xhci->scratchpad_pool = dma_pool_create("xhci scratchpad buffer pool",
+			dev, xhci->page_size,
+			xhci->page_size, xhci->page_size);
+	if (!xhci->scratchpad_pool)
+		goto fail_sp4;
+
 	for (i = 0; i < num_sp; i++) {
 		dma_addr_t dma;
-		void *buf = dma_alloc_coherent(dev, xhci->page_size, &dma,
-				flags);
+		void *buf = dma_pool_zalloc(xhci->scratchpad_pool, flags, &dma);
 		if (!buf)
-			goto fail_sp4;
+			goto fail_sp5;
 
 		xhci->scratchpad->sp_array[i] = dma;
 		xhci->scratchpad->sp_buffers[i] = buf;
@@ -1723,13 +1729,15 @@ static int scratchpad_alloc(struct xhci_hcd *xhci, gfp_t flags)
 
 	return 0;
 
- fail_sp4:
+ fail_sp5:
 	for (i = i - 1; i >= 0; i--) {
-		dma_free_coherent(dev, xhci->page_size,
+		dma_pool_free(xhci->scratchpad_pool,
 				    xhci->scratchpad->sp_buffers[i],
 				    xhci->scratchpad->sp_array[i]);
 	}
+	dma_pool_destroy(xhci->scratchpad_pool);
 
+ fail_sp4:
 	kfree(xhci->scratchpad->sp_buffers);
 
  fail_sp3:
@@ -1757,10 +1765,11 @@ static void scratchpad_free(struct xhci_hcd *xhci)
 	num_sp = HCS_MAX_SCRATCHPAD(xhci->hcs_params2);
 
 	for (i = 0; i < num_sp; i++) {
-		dma_free_coherent(dev, xhci->page_size,
+		dma_pool_free(xhci->scratchpad_pool,
 				    xhci->scratchpad->sp_buffers[i],
 				    xhci->scratchpad->sp_array[i]);
 	}
+	dma_pool_destroy(xhci->scratchpad_pool);
 	kfree(xhci->scratchpad->sp_buffers);
 	dma_free_coherent(dev, num_sp * sizeof(u64),
 			    xhci->scratchpad->sp_array,
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 00d2578..d029398 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1758,6 +1758,7 @@ struct xhci_hcd {
 	struct dma_pool	*segment_pool;
 	struct dma_pool	*small_streams_pool;
 	struct dma_pool	*medium_streams_pool;
+	struct dma_pool	*scratchpad_pool;
 
 	/* Host controller watchdog timer structures */
 	unsigned int		xhc_state;
-- 
2.7.4

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