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Message-ID: <20130320174947.GB31929@xanatos>
Date:	Wed, 20 Mar 2013 10:49:47 -0700
From:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
To:	Vivek Gautam <gautam.vivek@...sung.com>
Cc:	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	gregkh@...uxfoundation.org
Subject: Re: [PATCH] usb: xhci: Fix TRB transfer length macro used for Event
 TRB.

On Wed, Mar 20, 2013 at 03:48:40PM +0530, Vivek Gautam wrote:
> Use proper macro while extracting TRB transfer length from
> Transfer event TRBs. Adding a macro EVENT_TRB_LEN (bits 0:23)
> for the same, and use it instead of TRB_LEN (bits 0:16) in
> case of event TRBs.

Thanks for the patch!  Comments below.

> Signed-off-by: Vivek gautam <gautam.vivek@...sung.com>
> ---
>  drivers/usb/host/xhci-ring.c |   45 +++++++++++++++++++++++------------------
>  drivers/usb/host/xhci.h      |    4 +++
>  2 files changed, 29 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index 8828754..fe59a30 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -2027,8 +2027,8 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
>  		if (event_trb != ep_ring->dequeue &&
>  				event_trb != td->last_trb)
>  			td->urb->actual_length =
> -				td->urb->transfer_buffer_length
> -				- TRB_LEN(le32_to_cpu(event->transfer_len));
> +				td->urb->transfer_buffer_length -
> +				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));

This looks fine.

>  		else
>  			td->urb->actual_length = 0;
>  
> @@ -2060,7 +2060,7 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
>  		/* Maybe the event was for the data stage? */
>  			td->urb->actual_length =
>  				td->urb->transfer_buffer_length -
> -				TRB_LEN(le32_to_cpu(event->transfer_len));
> +				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));

Fine

>  			xhci_dbg(xhci, "Waiting for status "
>  					"stage event\n");
>  			return 0;
> @@ -2096,7 +2096,7 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
>  	/* handle completion code */
>  	switch (trb_comp_code) {
>  	case COMP_SUCCESS:
> -		if (TRB_LEN(le32_to_cpu(event->transfer_len)) == 0) {
> +		if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) == 0) {

Fine

>  			frame->status = 0;
>  			break;
>  		}
> @@ -2137,11 +2137,13 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,

This bit of code is looping through the endpoint ring, and cur_trb
points to a transfer TRB on the endpoint ring.  We're adding up the
transfer buffer lengths, up to the TRB that had a completion event.

>  		     cur_seg = ep_ring->deq_seg; cur_trb != event_trb;
>  		     next_trb(xhci, ep_ring, &cur_seg, &cur_trb)) {
>  			if (!TRB_TYPE_NOOP_LE32(cur_trb->generic.field[3]) &&
> -			    !TRB_TYPE_LINK_LE32(cur_trb->generic.field[3]))
> -				len += TRB_LEN(le32_to_cpu(cur_trb->generic.field[2]));
> +			    !TRB_TYPE_LINK_LE32(cur_trb->generic.field[3])) {
> +				len += EVENT_TRB_LEN(le32_to_cpu
> +						(cur_trb->generic.field[2]));
> +			}

In this case, cur_trb points to a transfer TRB, not an event TRB.  So
this instance still needs to use the TRB_LEN macro.

Adding the extra braces here makes it hard to review.  Please don't add
extra braces, or do so in a second patch if it really bothers you.

>  		}
> -		len += TRB_LEN(le32_to_cpu(cur_trb->generic.field[2])) -
> -			TRB_LEN(le32_to_cpu(event->transfer_len));
> +		len += EVENT_TRB_LEN(le32_to_cpu(cur_trb->generic.field[2])) -
> +			EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));

Here, cur_trb points to a transfer TRB, and event points to an event
TRB.  So you need to use the TRB_LEN macro for the first line, and the
EVENT_TRB_LEN macro for the second line.

>  
>  		if (trb_comp_code != COMP_STOP_INVAL) {
>  			frame->actual_length = len;
> @@ -2199,7 +2201,7 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
>  	case COMP_SUCCESS:
>  		/* Double check that the HW transferred everything. */
>  		if (event_trb != td->last_trb ||
> -				TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
> +		    EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {

Fine.

>  			xhci_warn(xhci, "WARN Successful completion "
>  					"on short TX\n");
>  			if (td->urb->transfer_flags & URB_SHORT_NOT_OK)
> @@ -2225,20 +2227,21 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
>  	if (trb_comp_code == COMP_SHORT_TX)
>  		xhci_dbg(xhci, "ep %#x - asked for %d bytes, "
>  				"%d bytes untransferred\n",
> -				td->urb->ep->desc.bEndpointAddress,
> -				td->urb->transfer_buffer_length,
> -				TRB_LEN(le32_to_cpu(event->transfer_len)));
> +			      td->urb->ep->desc.bEndpointAddress,
> +			      td->urb->transfer_buffer_length,
> +			      EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)));

Please don't change indentation.  I know it's a pain to keep lines
within 80 chars, but I would rather have a longer line than non-standard
indentation.  The macro change is fine.

>  	/* Fast path - was this the last TRB in the TD for this URB? */
>  	if (event_trb == td->last_trb) {
> -		if (TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
> +		if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
>  			td->urb->actual_length =
>  				td->urb->transfer_buffer_length -
> -				TRB_LEN(le32_to_cpu(event->transfer_len));
> +				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
>  			if (td->urb->transfer_buffer_length <
>  					td->urb->actual_length) {
>  				xhci_warn(xhci, "HC gave bad length "
>  						"of %d bytes left\n",
> -					  TRB_LEN(le32_to_cpu(event->transfer_len)));
> +					EVENT_TRB_LEN(le32_to_cpu
> +							(event->transfer_len)));

This chunk is fine.

>  				td->urb->actual_length = 0;
>  				if (td->urb->transfer_flags & URB_SHORT_NOT_OK)
>  					*status = -EREMOTEIO;
> @@ -2270,17 +2273,19 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
>  				cur_trb != event_trb;
>  				next_trb(xhci, ep_ring, &cur_seg, &cur_trb)) {
>  			if (!TRB_TYPE_NOOP_LE32(cur_trb->generic.field[3]) &&
> -			    !TRB_TYPE_LINK_LE32(cur_trb->generic.field[3]))
> +			    !TRB_TYPE_LINK_LE32(cur_trb->generic.field[3])) {
>  				td->urb->actual_length +=
> -					TRB_LEN(le32_to_cpu(cur_trb->generic.field[2]));
> +					EVENT_TRB_LEN(le32_to_cpu
> +						(cur_trb->generic.field[2]));
> +		     }

Again, this is walking the endpoint ring's transfer TRBs to add up the
transferred length, and thus those last two lines should still use the
TRB_LEN macro.

Also, don't add extra braces to one-line blocks.  And why was the
indentation on the curly braces so odd?  Please only use tabs.

>  		}
>  		/* If the ring didn't stop on a Link or No-op TRB, add
>  		 * in the actual bytes transferred from the Normal TRB
>  		 */
>  		if (trb_comp_code != COMP_STOP_INVAL)
>  			td->urb->actual_length +=
> -				TRB_LEN(le32_to_cpu(cur_trb->generic.field[2])) -
> -				TRB_LEN(le32_to_cpu(event->transfer_len));
> +			  EVENT_TRB_LEN(le32_to_cpu(cur_trb->generic.field[2]))
> +			  - EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));

cur_trb needs to use the TRB_LEN, and event needs to use the
EVENT_TRB_LEN macro.

>  	}
>  
>  	return finish_td(xhci, td, event_trb, event, ep, status, false);
> @@ -2368,7 +2373,7 @@ static int handle_tx_event(struct xhci_hcd *xhci,
>  	 * transfer type
>  	 */
>  	case COMP_SUCCESS:
> -		if (TRB_LEN(le32_to_cpu(event->transfer_len)) == 0)
> +		if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) == 0)

Fine.

>  			break;
>  		if (xhci->quirks & XHCI_TRUST_TX_LENGTH)
>  			trb_comp_code = COMP_SHORT_TX;
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index f791bd0..61f71ed 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -972,6 +972,10 @@ struct xhci_transfer_event {
>  	__le32	flags;
>  };
>  
> +/* Transfer event TRB length bit mask */
> +/* bits 0:23 */
> +#define	EVENT_TRB_LEN(p)		((p) & 0xffffff)
> +
>  /** Transfer Event bit fields **/
>  #define	TRB_TO_EP_ID(p)	(((p) >> 16) & 0x1f)
>  
> -- 
> 1.7.6.5
>

Can you correct these and resubmit?  Thanks!

Sarah Sharp
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