[PATCH v2] usb: cdns3: Optimize DMA request buffer allocation

[PATCH v2] usb: cdns3: Optimize DMA request buffer allocation

[Sanket Parmar]

dma_alloc_coherent() might fail on the platform with a small
DMA region.

To avoid such failure in cdns3_prepare_aligned_request_buf(),
dma_alloc_coherent() is replaced with dma_alloc_noncoherent()
to allocate aligned request buffer of dynamic length.

Reported-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Sanket Parmar <sparmar@cadence.com>
---

Changelog:
v2:
- used dma_*_noncoherent() APIs
- changed the commit log

 drivers/usb/cdns3/cdns3-gadget.c | 30 ++++++++++++++++++++++++------
 drivers/usb/cdns3/cdns3-gadget.h |  2 ++
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 0b892a2..126087b 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -819,9 +819,15 @@ void cdns3_gadget_giveback(struct cdns3_endpoint *priv_ep,
 					priv_ep->dir);
 
 	if ((priv_req->flags & REQUEST_UNALIGNED) &&
-	    priv_ep->dir == USB_DIR_OUT && !request->status)
+	    priv_ep->dir == USB_DIR_OUT && !request->status) {
+		/* Make DMA buffer CPU accessible */
+		dma_sync_single_for_cpu(priv_dev->sysdev,
+			priv_req->aligned_buf->dma,
+			priv_req->aligned_buf->size,
+			priv_req->aligned_buf->dir);
 		memcpy(request->buf, priv_req->aligned_buf->buf,
 		       request->length);
+	}
 
 	priv_req->flags &= ~(REQUEST_PENDING | REQUEST_UNALIGNED);
 	/* All TRBs have finished, clear the counter */
@@ -883,8 +889,8 @@ 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);
+			dma_free_noncoherent(priv_dev->sysdev, buf->size,
+					  buf->buf, buf->dma, buf->dir);
 			kfree(buf);
 			spin_lock_irqsave(&priv_dev->lock, flags);
 		}
@@ -911,10 +917,13 @@ static int cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
 			return -ENOMEM;
 
 		buf->size = priv_req->request.length;
+		buf->dir = usb_endpoint_dir_in(priv_ep->endpoint.desc) ?
+			DMA_TO_DEVICE : DMA_FROM_DEVICE;
 
-		buf->buf = dma_alloc_coherent(priv_dev->sysdev,
+		buf->buf = dma_alloc_noncoherent(priv_dev->sysdev,
 					      buf->size,
 					      &buf->dma,
+					      buf->dir,
 					      GFP_ATOMIC);
 		if (!buf->buf) {
 			kfree(buf);
@@ -936,10 +945,18 @@ static int cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
 	}
 
 	if (priv_ep->dir == USB_DIR_IN) {
+		/* Make DMA buffer CPU accessible */
+		dma_sync_single_for_cpu(priv_dev->sysdev,
+			buf->dma, buf->size, buf->dir);
 		memcpy(buf->buf, priv_req->request.buf,
 		       priv_req->request.length);
 	}
 
+	/* Transfer DMA buffer ownership back to device */
+	dma_sync_single_for_device(priv_dev->sysdev,
+			buf->dma, buf->size, buf->dir);
+
+
 	priv_req->flags |= REQUEST_UNALIGNED;
 	trace_cdns3_prepare_aligned_request(priv_req);
 
@@ -3088,9 +3105,10 @@ 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,
+		dma_free_noncoherent(priv_dev->sysdev, buf->size,
 				  buf->buf,
-				  buf->dma);
+				  buf->dma,
+				  buf->dir);
 
 		list_del(&buf->list);
 		kfree(buf);
diff --git a/drivers/usb/cdns3/cdns3-gadget.h b/drivers/usb/cdns3/cdns3-gadget.h
index ecf9b91..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;
 };
-- 
2.4.5

Re: [PATCH v2] usb: cdns3: Optimize DMA request buffer allocation

[Christoph Hellwig]

On Wed, Mar 17, 2021 at 08:13:59PM +0100, Sanket Parmar wrote:
> dma_alloc_coherent() might fail on the platform with a small
> DMA region.
> 
> To avoid such failure in cdns3_prepare_aligned_request_buf(),
> dma_alloc_coherent() is replaced with dma_alloc_noncoherent()
> to allocate aligned request buffer of dynamic length.
> 
> Reported-by: Aswath Govindraju <a-govindraju@ti.com>
> Signed-off-by: Sanket Parmar <sparmar@cadence.com>

Looks good to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v2] usb: cdns3: Optimize DMA request buffer allocation

[Peter Chen]

On 21-03-18 07:32:45, Christoph Hellwig wrote:
> On Wed, Mar 17, 2021 at 08:13:59PM +0100, Sanket Parmar wrote:
> > dma_alloc_coherent() might fail on the platform with a small
> > DMA region.
> > 
> > To avoid such failure in cdns3_prepare_aligned_request_buf(),
> > dma_alloc_coherent() is replaced with dma_alloc_noncoherent()
> > to allocate aligned request buffer of dynamic length.
> > 
> > Reported-by: Aswath Govindraju <a-govindraju@ti.com>
> > Signed-off-by: Sanket Parmar <sparmar@cadence.com>
> 
> Looks good to me:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Hi Christoph,

I would like to confirm the dma_alloc_noncoherent allocates the memory
less than PAGE_SIZE if buffer size it would like to allocate is small
(eg, 64 bytes)? 

-- 

Thanks,
Peter Chen

Re: [PATCH v2] usb: cdns3: Optimize DMA request buffer allocation

[Peter Chen]

On 21-03-17 20:13:59, Sanket Parmar wrote:
> dma_alloc_coherent() might fail on the platform with a small
> DMA region.
> 
> To avoid such failure in cdns3_prepare_aligned_request_buf(),
> dma_alloc_coherent() is replaced with dma_alloc_noncoherent()
> to allocate aligned request buffer of dynamic length.
> 
> Reported-by: Aswath Govindraju <a-govindraju@ti.com>
> Signed-off-by: Sanket Parmar <sparmar@cadence.com>
> ---
> 
> Changelog:
> v2:
> - used dma_*_noncoherent() APIs
> - changed the commit log
> 
>  drivers/usb/cdns3/cdns3-gadget.c | 30 ++++++++++++++++++++++++------
>  drivers/usb/cdns3/cdns3-gadget.h |  2 ++
>  2 files changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
> index 0b892a2..126087b 100644
> --- a/drivers/usb/cdns3/cdns3-gadget.c
> +++ b/drivers/usb/cdns3/cdns3-gadget.c
> @@ -819,9 +819,15 @@ void cdns3_gadget_giveback(struct cdns3_endpoint *priv_ep,
>  					priv_ep->dir);
>  
>  	if ((priv_req->flags & REQUEST_UNALIGNED) &&
> -	    priv_ep->dir == USB_DIR_OUT && !request->status)
> +	    priv_ep->dir == USB_DIR_OUT && !request->status) {
> +		/* Make DMA buffer CPU accessible */
> +		dma_sync_single_for_cpu(priv_dev->sysdev,
> +			priv_req->aligned_buf->dma,
> +			priv_req->aligned_buf->size,
> +			priv_req->aligned_buf->dir);
>  		memcpy(request->buf, priv_req->aligned_buf->buf,
>  		       request->length);
> +	}
>  
>  	priv_req->flags &= ~(REQUEST_PENDING | REQUEST_UNALIGNED);
>  	/* All TRBs have finished, clear the counter */
> @@ -883,8 +889,8 @@ 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);
> +			dma_free_noncoherent(priv_dev->sysdev, buf->size,
> +					  buf->buf, buf->dma, buf->dir);
>  			kfree(buf);
>  			spin_lock_irqsave(&priv_dev->lock, flags);
>  		}
> @@ -911,10 +917,13 @@ static int cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
>  			return -ENOMEM;
>  
>  		buf->size = priv_req->request.length;
> +		buf->dir = usb_endpoint_dir_in(priv_ep->endpoint.desc) ?
> +			DMA_TO_DEVICE : DMA_FROM_DEVICE;
>  
> -		buf->buf = dma_alloc_coherent(priv_dev->sysdev,
> +		buf->buf = dma_alloc_noncoherent(priv_dev->sysdev,
>  					      buf->size,
>  					      &buf->dma,
> +					      buf->dir,
>  					      GFP_ATOMIC);
>  		if (!buf->buf) {
>  			kfree(buf);
> @@ -936,10 +945,18 @@ static int cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
>  	}
>  
>  	if (priv_ep->dir == USB_DIR_IN) {
> +		/* Make DMA buffer CPU accessible */
> +		dma_sync_single_for_cpu(priv_dev->sysdev,
> +			buf->dma, buf->size, buf->dir);
>  		memcpy(buf->buf, priv_req->request.buf,
>  		       priv_req->request.length);
>  	}
>  
> +	/* Transfer DMA buffer ownership back to device */
> +	dma_sync_single_for_device(priv_dev->sysdev,
> +			buf->dma, buf->size, buf->dir);
> +
> +

One more blank line.

Otherwise, it seems OK for me.

>  	priv_req->flags |= REQUEST_UNALIGNED;
>  	trace_cdns3_prepare_aligned_request(priv_req);
>  
> @@ -3088,9 +3105,10 @@ 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,
> +		dma_free_noncoherent(priv_dev->sysdev, buf->size,
>  				  buf->buf,
> -				  buf->dma);
> +				  buf->dma,
> +				  buf->dir);
>  
>  		list_del(&buf->list);
>  		kfree(buf);
> diff --git a/drivers/usb/cdns3/cdns3-gadget.h b/drivers/usb/cdns3/cdns3-gadget.h
> index ecf9b91..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;
>  };
> -- 
> 2.4.5
> 

-- 

Thanks,
Peter Chen

RE: [PATCH v2] usb: cdns3: Optimize DMA request buffer allocation

[Sanket Parmar]

Hi Peter,

> On 21-03-17 20:13:59, Sanket Parmar wrote:
> > dma_alloc_coherent() might fail on the platform with a small
> > DMA region.
> >
> > To avoid such failure in cdns3_prepare_aligned_request_buf(),
> > dma_alloc_coherent() is replaced with dma_alloc_noncoherent()
> > to allocate aligned request buffer of dynamic length.
> >
> > Reported-by: Aswath Govindraju <a-govindraju@ti.com>
> > Signed-off-by: Sanket Parmar <sparmar@cadence.com>
> > ---
> >
> > Changelog:
> > v2:
> > - used dma_*_noncoherent() APIs
> > - changed the commit log
> >
> >  drivers/usb/cdns3/cdns3-gadget.c | 30 ++++++++++++++++++++++++-----
> -
> >  drivers/usb/cdns3/cdns3-gadget.h |  2 ++
> >  2 files changed, 26 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-
> gadget.c
> > index 0b892a2..126087b 100644
> > --- a/drivers/usb/cdns3/cdns3-gadget.c
> > +++ b/drivers/usb/cdns3/cdns3-gadget.c
> > @@ -819,9 +819,15 @@ void cdns3_gadget_giveback(struct
> cdns3_endpoint *priv_ep,
> >  					priv_ep->dir);
> >
> >  	if ((priv_req->flags & REQUEST_UNALIGNED) &&
> > -	    priv_ep->dir == USB_DIR_OUT && !request->status)
> > +	    priv_ep->dir == USB_DIR_OUT && !request->status) {
> > +		/* Make DMA buffer CPU accessible */
> > +		dma_sync_single_for_cpu(priv_dev->sysdev,
> > +			priv_req->aligned_buf->dma,
> > +			priv_req->aligned_buf->size,
> > +			priv_req->aligned_buf->dir);
> >  		memcpy(request->buf, priv_req->aligned_buf->buf,
> >  		       request->length);
> > +	}
> >
> >  	priv_req->flags &= ~(REQUEST_PENDING | REQUEST_UNALIGNED);
> >  	/* All TRBs have finished, clear the counter */
> > @@ -883,8 +889,8 @@ 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);
> > +			dma_free_noncoherent(priv_dev->sysdev, buf-
> >size,
> > +					  buf->buf, buf->dma, buf->dir);
> >  			kfree(buf);
> >  			spin_lock_irqsave(&priv_dev->lock, flags);
> >  		}
> > @@ -911,10 +917,13 @@ static int
> cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
> >  			return -ENOMEM;
> >
> >  		buf->size = priv_req->request.length;
> > +		buf->dir = usb_endpoint_dir_in(priv_ep->endpoint.desc) ?
> > +			DMA_TO_DEVICE : DMA_FROM_DEVICE;
> >
> > -		buf->buf = dma_alloc_coherent(priv_dev->sysdev,
> > +		buf->buf = dma_alloc_noncoherent(priv_dev->sysdev,
> >  					      buf->size,
> >  					      &buf->dma,
> > +					      buf->dir,
> >  					      GFP_ATOMIC);
> >  		if (!buf->buf) {
> >  			kfree(buf);
> > @@ -936,10 +945,18 @@ static int
> cdns3_prepare_aligned_request_buf(struct cdns3_request *priv_req)
> >  	}
> >
> >  	if (priv_ep->dir == USB_DIR_IN) {
> > +		/* Make DMA buffer CPU accessible */
> > +		dma_sync_single_for_cpu(priv_dev->sysdev,
> > +			buf->dma, buf->size, buf->dir);
> >  		memcpy(buf->buf, priv_req->request.buf,
> >  		       priv_req->request.length);
> >  	}
> >
> > +	/* Transfer DMA buffer ownership back to device */
> > +	dma_sync_single_for_device(priv_dev->sysdev,
> > +			buf->dma, buf->size, buf->dir);
> > +
> > +
> 
> One more blank line.
> 
> Otherwise, it seems OK for me.

I have remove this blank line. New patch has been posted already.

> 
> >  	priv_req->flags |= REQUEST_UNALIGNED;
> >  	trace_cdns3_prepare_aligned_request(priv_req);
> >
> > @@ -3088,9 +3105,10 @@ 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,
> > +		dma_free_noncoherent(priv_dev->sysdev, buf->size,
> >  				  buf->buf,
> > -				  buf->dma);
> > +				  buf->dma,
> > +				  buf->dir);
> >
> >  		list_del(&buf->list);
> >  		kfree(buf);
> > diff --git a/drivers/usb/cdns3/cdns3-gadget.h b/drivers/usb/cdns3/cdns3-
> gadget.h
> > index ecf9b91..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;
> >  };
> > --
> > 2.4.5
> >
> 
> --
> 
> Thanks,
> Peter Chen

Thanks,
Sanket