[PATCH] usb: cdns3: Coherent memory allocation optimization

[Sanket Parmar]

Allocation of DMA coherent memory in atomic context using
dma_alloc_coherent() might fail on some platform. To fix it,
Replaced dma_alloc_coherent() with dma_pool API to allocate a
smaller chunk of DMA coherent memory for TRB rings.

Also in cdns3_prepare_aligned_request_buf(), replaced
dma_alloc_coherent() with kmalloc and dma_map API to allocate
aligned request buffer of dynamic length.

Fixes: commit 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Reported by: Aswath Govindraju <a-govindraju@xxxxxx>
Signed-off-by: Sanket Parmar <sparmar@xxxxxxxxxxx>
---
 drivers/usb/cdns3/cdns3-gadget.c |  115 ++++++++++++++++++++++---------------
 drivers/usb/cdns3/cdns3-gadget.h |    3 +
 2 files changed, 71 insertions(+), 47 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 582bfec..5fd6993 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -59,6 +59,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/usb/gadget.h>
 #include <linux/module.h>
+#include <linux/dmapool.h>
 #include <linux/iopoll.h>
 
 #include "core.h"
@@ -190,29 +191,13 @@ dma_addr_t cdns3_trb_virt_to_dma(struct cdns3_endpoint *priv_ep,
 	return priv_ep->trb_pool_dma + offset;
 }
 
-static int cdns3_ring_size(struct cdns3_endpoint *priv_ep)
-{
-	switch (priv_ep->type) {
-	case USB_ENDPOINT_XFER_ISOC:
-		return TRB_ISO_RING_SIZE;
-	case USB_ENDPOINT_XFER_CONTROL:
-		return TRB_CTRL_RING_SIZE;
-	default:
-		if (priv_ep->use_streams)
-			return TRB_STREAM_RING_SIZE;
-		else
-			return TRB_RING_SIZE;
-	}
-}
-
 static void cdns3_free_trb_pool(struct cdns3_endpoint *priv_ep)
 {
 	struct cdns3_device *priv_dev = priv_ep->cdns3_dev;
 
 	if (priv_ep->trb_pool) {
-		dma_free_coherent(priv_dev->sysdev,
-				  cdns3_ring_size(priv_ep),
-				  priv_ep->trb_pool, priv_ep->trb_pool_dma);
+		dma_pool_free(priv_dev->eps_dma_pool,
+				priv_ep->trb_pool, priv_ep->trb_pool_dma);
 		priv_ep->trb_pool = NULL;
 	}
 }
@@ -226,7 +211,7 @@ static void cdns3_free_trb_pool(struct cdns3_endpoint *priv_ep)
 int cdns3_allocate_trb_pool(struct cdns3_endpoint *priv_ep)
 {
 	struct cdns3_device *priv_dev = priv_ep->cdns3_dev;
-	int ring_size = cdns3_ring_size(priv_ep);
+	int ring_size = TRB_RING_SIZE;
 	int num_trbs = ring_size / TRB_SIZE;
 	struct cdns3_trb *link_trb;
 
@@ -234,10 +219,10 @@ int cdns3_allocate_trb_pool(struct cdns3_endpoint *priv_ep)
 		cdns3_free_trb_pool(priv_ep);
 
 	if (!priv_ep->trb_pool) {
-		priv_ep->trb_pool = dma_alloc_coherent(priv_dev->sysdev,
-						       ring_size,
-						       &priv_ep->trb_pool_dma,
-						       GFP_DMA32 | GFP_ATOMIC);
+		priv_ep->trb_pool = dma_pool_alloc(priv_dev->eps_dma_pool,
+						GFP_DMA32 | GFP_ATOMIC,
+						&priv_ep->trb_pool_dma);
+
 		if (!priv_ep->trb_pool)
 			return -ENOMEM;
 
@@ -833,10 +818,26 @@ void cdns3_gadget_giveback(struct cdns3_endpoint *priv_ep,
 	usb_gadget_unmap_request_by_dev(priv_dev->sysdev, request,
 					priv_ep->dir);
 
-	if ((priv_req->flags & REQUEST_UNALIGNED) &&
-	    priv_ep->dir == USB_DIR_OUT && !request->status)
-		memcpy(request->buf, priv_req->aligned_buf->buf,
-		       request->length);
+	if ((priv_req->flags & REQUEST_UNALIGNED) && priv_req->aligned_buf) {
+		struct cdns3_aligned_buf *buf;
+
+		buf = priv_req->aligned_buf;
+		dma_unmap_single(priv_dev->sysdev, buf->dma, buf->size,
+			buf->dir);
+		priv_req->flags &= ~REQUEST_UNALIGNED;
+
+		if (priv_ep->dir == USB_DIR_OUT && !request->status) {
+			memcpy(request->buf, priv_req->aligned_buf->buf,
+			       request->length);
+		}
+
+		trace_cdns3_free_aligned_request(priv_req);
+		priv_req->aligned_buf->in_use = 0;
+		queue_work(system_freezable_wq,
+			   &priv_dev->aligned_buf_wq);
+		priv_req->aligned_buf = NULL;
+
+	}
 
 	priv_req->flags &= ~(REQUEST_PENDING | REQUEST_UNALIGNED);
 	/* All TRBs have finished, clear the counter */
@@ -898,8 +899,7 @@ static void cdns3_free_aligned_request_buf(struct work_struct *work)
 			 * interrupts.
 			 */
 			spin_unlock_irqrestore(&priv_dev->lock, flags);
-			dma_free_coherent(priv_dev->sysdev, buf->size,
-					  buf->buf, buf->dma);
+			kfree(buf->buf);
 			kfree(buf);
 			spin_lock_irqsave(&priv_dev->lock, flags);
 		}
@@ -925,27 +925,16 @@ static int cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
 		if (!buf)
 			return -ENOMEM;
 
-		buf->size = priv_req->request.length;
+		buf->size = usb_endpoint_dir_out(priv_ep->endpoint.desc) ?
+				usb_ep_align(&(priv_ep->endpoint), priv_req->request.length)
+				: priv_req->request.length;
 
-		buf->buf = dma_alloc_coherent(priv_dev->sysdev,
-					      buf->size,
-					      &buf->dma,
-					      GFP_ATOMIC);
+		buf->buf = kmalloc(buf->size, GFP_ATOMIC);
 		if (!buf->buf) {
 			kfree(buf);
 			return -ENOMEM;
 		}
 
-		if (priv_req->aligned_buf) {
-			trace_cdns3_free_aligned_request(priv_req);
-			priv_req->aligned_buf->in_use = 0;
-			queue_work(system_freezable_wq,
-				   &priv_dev->aligned_buf_wq);
-		}
-
-		buf->in_use = 1;
-		priv_req->aligned_buf = buf;
-
 		list_add_tail(&buf->list,
 			      &priv_dev->aligned_buf_list);
 	}
@@ -955,6 +944,27 @@ static int cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
 		       priv_req->request.length);
 	}
 
+	if (priv_req->aligned_buf) {
+		trace_cdns3_free_aligned_request(priv_req);
+		priv_req->aligned_buf->in_use = 0;
+		queue_work(system_freezable_wq,
+			   &priv_dev->aligned_buf_wq);
+	}
+
+	buf->dir =  priv_ep->dir ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
+	buf->in_use = 1;
+	priv_req->aligned_buf = buf;
+
+	buf->dma = dma_map_single(priv_dev->sysdev, buf->buf, buf->size,
+				buf->dir);
+
+	if (dma_mapping_error(priv_dev->sysdev, buf->dma)) {
+		dev_err(priv_dev->dev, "Failed to map buffer\n");
+		kfree(buf->buf);
+		kfree(buf);
+		return -EFAULT;
+	}
+
 	priv_req->flags |= REQUEST_UNALIGNED;
 	trace_cdns3_prepare_aligned_request(priv_req);
 
@@ -3103,16 +3113,17 @@ static void cdns3_gadget_exit(struct cdns *cdns)
 		struct cdns3_aligned_buf *buf;
 
 		buf = cdns3_next_align_buf(&priv_dev->aligned_buf_list);
-		dma_free_coherent(priv_dev->sysdev, buf->size,
-				  buf->buf,
-				  buf->dma);
+		dma_unmap_single(priv_dev->sysdev, buf->dma, buf->size,
+			buf->dir);
 
 		list_del(&buf->list);
+		kfree(buf->buf);
 		kfree(buf);
 	}
 
 	dma_free_coherent(priv_dev->sysdev, 8, priv_dev->setup_buf,
 			  priv_dev->setup_dma);
+	dma_pool_destroy(priv_dev->eps_dma_pool);
 
 	kfree(priv_dev->zlp_buf);
 	usb_put_gadget(&priv_dev->gadget);
@@ -3185,6 +3196,14 @@ static int cdns3_gadget_start(struct cdns *cdns)
 	/* initialize endpoint container */
 	INIT_LIST_HEAD(&priv_dev->gadget.ep_list);
 	INIT_LIST_HEAD(&priv_dev->aligned_buf_list);
+	priv_dev->eps_dma_pool = dma_pool_create("cdns3_eps_dma_pool",
+						priv_dev->sysdev,
+						TRB_RING_SIZE, 8, 0);
+	if (!priv_dev->eps_dma_pool) {
+		dev_err(priv_dev->dev, "Failed to create TRB dma pool\n");
+		ret = -ENOMEM;
+		goto err1;
+	}
 
 	ret = cdns3_init_eps(priv_dev);
 	if (ret) {
@@ -3235,6 +3254,8 @@ static int cdns3_gadget_start(struct cdns *cdns)
 err2:
 	cdns3_free_all_eps(priv_dev);
 err1:
+	dma_pool_destroy(priv_dev->eps_dma_pool);
+
 	usb_put_gadget(&priv_dev->gadget);
 	cdns->gadget_dev = NULL;
 	return ret;
diff --git a/drivers/usb/cdns3/cdns3-gadget.h b/drivers/usb/cdns3/cdns3-gadget.h
index 21fa461..c5660f2 100644
--- a/drivers/usb/cdns3/cdns3-gadget.h
+++ b/drivers/usb/cdns3/cdns3-gadget.h
@@ -12,6 +12,7 @@
 #ifndef __LINUX_CDNS3_GADGET
 #define __LINUX_CDNS3_GADGET
 #include <linux/usb/gadget.h>
+#include <linux/dma-direction.h>
 
 /*
  * USBSS-DEV register interface.
@@ -1205,6 +1206,7 @@ struct cdns3_aligned_buf {
 	void			*buf;
 	dma_addr_t		dma;
 	u32			size;
+	enum dma_data_direction dir;
 	unsigned		in_use:1;
 	struct list_head	list;
 };
@@ -1298,6 +1300,7 @@ struct cdns3_device {
 
 	struct cdns3_usb_regs		__iomem *regs;
 
+	struct dma_pool			*eps_dma_pool;
 	struct usb_ctrlrequest		*setup_buf;
 	dma_addr_t			setup_dma;
 	void				*zlp_buf;
-- 
1.7.1