usb: wusbcore: combine iso transfer result frame reads when possible

When reading the transfer result data for an isochronous in request, if
the current frame actual_length is contiguous with the next frame and
actual_length is a multiple of the DTI endpoint max packet size, combine
the current frame with the next frame in a single URB.  This reduces the
number of URBs that must be submitted in that case which increases
performance and reduces CPU interrupt overhead.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/wusbcore/wa-xfer.c b/drivers/usb/wusbcore/wa-xfer.c
index 52c7259705e6567ae73bfe663340689b13dbdf09..f930bbb1a0ff0550976e89c3507a8108febc8887 100644 (file)
--- a/drivers/usb/wusbcore/wa-xfer.c
+++ b/drivers/usb/wusbcore/wa-xfer.c
@@ -2160,22 +2160,59 @@ static void wa_complete_remaining_xfer_segs(struct wa_xfer *xfer,
 }
 
 /* Populate the wa->buf_in_urb based on the current isoc transfer state. */
-static void __wa_populate_buf_in_urb_isoc(struct wahc *wa, struct wa_xfer *xfer,
-       struct wa_seg *seg, int curr_iso_frame)
+static int __wa_populate_buf_in_urb_isoc(struct wahc *wa, struct wa_xfer *xfer,
+       struct wa_seg *seg)
 {
+       int urb_start_frame = seg->isoc_frame_index + seg->isoc_frame_offset;
+       int seg_index, total_len = 0, urb_frame_index = urb_start_frame;
+       struct usb_iso_packet_descriptor *iso_frame_desc =
+                                               xfer->urb->iso_frame_desc;
+       const int dti_packet_size = usb_endpoint_maxp(wa->dti_epd);
+       int next_frame_contiguous;
+       struct usb_iso_packet_descriptor *iso_frame;
+
        BUG_ON(wa->buf_in_urb->status == -EINPROGRESS);
 
+       /*
+        * If the current frame actual_length is contiguous with the next frame
+        * and actual_length is a multiple of the DTI endpoint max packet size,
+        * combine the current frame with the next frame in a single URB.  This
+        * reduces the number of URBs that must be submitted in that case.
+        */
+       seg_index = seg->isoc_frame_index;
+       do {
+               next_frame_contiguous = 0;
+
+               iso_frame = &iso_frame_desc[urb_frame_index];
+               total_len += iso_frame->actual_length;
+               ++urb_frame_index;
+               ++seg_index;
+
+               if (seg_index < seg->isoc_frame_count) {
+                       struct usb_iso_packet_descriptor *next_iso_frame;
+
+                       next_iso_frame = &iso_frame_desc[urb_frame_index];
+
+                       if ((iso_frame->offset + iso_frame->actual_length) ==
+                               next_iso_frame->offset)
+                               next_frame_contiguous = 1;
+               }
+       } while (next_frame_contiguous
+                       && ((iso_frame->actual_length % dti_packet_size) == 0));
+
        /* this should always be 0 before a resubmit. */
        wa->buf_in_urb->num_mapped_sgs  = 0;
        wa->buf_in_urb->transfer_dma = xfer->urb->transfer_dma +
-               xfer->urb->iso_frame_desc[curr_iso_frame].offset;
-       wa->buf_in_urb->transfer_buffer_length =
-               xfer->urb->iso_frame_desc[curr_iso_frame].actual_length;
+               iso_frame_desc[urb_start_frame].offset;
+       wa->buf_in_urb->transfer_buffer_length = total_len;
        wa->buf_in_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
        wa->buf_in_urb->transfer_buffer = NULL;
        wa->buf_in_urb->sg = NULL;
        wa->buf_in_urb->num_sgs = 0;
        wa->buf_in_urb->context = seg;
+
+       /* return the number of frames included in this URB. */
+       return seg_index - seg->isoc_frame_index;
 }
 
 /* Populate the wa->buf_in_urb based on the current transfer state. */
@@ -2458,19 +2495,20 @@ static int wa_process_iso_packet_status(struct wahc *wa, struct urb *urb)
        }
 
        if (xfer->is_inbound && data_frame_count) {
-               int result;
+               int result, urb_frame_count;
 
                seg->isoc_frame_index = first_frame_index;
                /* submit a read URB for the first frame with data. */
-               __wa_populate_buf_in_urb_isoc(wa, xfer, seg,
-                       seg->isoc_frame_index + seg->isoc_frame_offset);
+               urb_frame_count = __wa_populate_buf_in_urb_isoc(wa, xfer, seg);
+               /* advance index to start of next read URB. */
+               seg->isoc_frame_index += urb_frame_count;
 
                result = usb_submit_urb(wa->buf_in_urb, GFP_ATOMIC);
                if (result < 0) {
                        dev_err(dev, "DTI Error: Could not submit buf in URB (%d)",
                                result);
                        wa_reset_all(wa);
-               } else if (data_frame_count > 1)
+               } else if (data_frame_count > urb_frame_count)
                        /* If we need to read multiple frames, set DTI busy. */
                        dti_busy = 1;
        } else {
@@ -2511,8 +2549,9 @@ static void wa_buf_in_cb(struct urb *urb)
        struct wahc *wa;
        struct device *dev;
        struct wa_rpipe *rpipe;
-       unsigned rpipe_ready = 0, seg_index, isoc_data_frame_count = 0;
+       unsigned rpipe_ready = 0, isoc_data_frame_count = 0;
        unsigned long flags;
+       int resubmit_dti = 0;
        u8 done = 0;
 
        /* free the sg if it was used. */
@@ -2524,17 +2563,16 @@ static void wa_buf_in_cb(struct urb *urb)
        dev = &wa->usb_iface->dev;
 
        if (usb_pipeisoc(xfer->urb->pipe)) {
+               struct usb_iso_packet_descriptor *iso_frame_desc =
+                       xfer->urb->iso_frame_desc;
+               int     seg_index;
+
                /*
-                * Find the next isoc frame with data.  Bail out after
-                * isoc_data_frame_count > 1 since there is no need to walk
-                * the entire frame array.  We just need to know if
-                * isoc_data_frame_count is 0, 1, or >1.
+                * Find the next isoc frame with data and count how many
+                * frames with data remain.
                 */
-               seg_index = seg->isoc_frame_index + 1;
-               while ((seg_index < seg->isoc_frame_count)
-                       && (isoc_data_frame_count <= 1)) {
-                       struct usb_iso_packet_descriptor *iso_frame_desc =
-                               xfer->urb->iso_frame_desc;
+               seg_index = seg->isoc_frame_index;
+               while (seg_index < seg->isoc_frame_count) {
                        const int urb_frame_index =
                                seg->isoc_frame_offset + seg_index;
 
@@ -2555,16 +2593,28 @@ static void wa_buf_in_cb(struct urb *urb)
 
                seg->result += urb->actual_length;
                if (isoc_data_frame_count > 0) {
-                       int result;
-                       /* submit a read URB for the first frame with data. */
-                       __wa_populate_buf_in_urb_isoc(wa, xfer, seg,
-                               seg->isoc_frame_index + seg->isoc_frame_offset);
+                       int result, urb_frame_count;
+
+                       /* submit a read URB for the next frame with data. */
+                       urb_frame_count = __wa_populate_buf_in_urb_isoc(wa,
+                                xfer, seg);
+                       /* advance index to start of next read URB. */
+                       seg->isoc_frame_index += urb_frame_count;
                        result = usb_submit_urb(wa->buf_in_urb, GFP_ATOMIC);
                        if (result < 0) {
                                dev_err(dev, "DTI Error: Could not submit buf in URB (%d)",
                                        result);
                                wa_reset_all(wa);
                        }
+                       /*
+                        * If we are in this callback and
+                        * isoc_data_frame_count > 0, it means that the dti_urb
+                        * submission was delayed in wa_dti_cb.  Once
+                        * we submit the last buf_in_urb, we can submit the
+                        * delayed dti_urb.
+                        */
+                         resubmit_dti = (isoc_data_frame_count ==
+                                                       urb_frame_count);
                } else {
                        rpipe = xfer->ep->hcpriv;
                        dev_dbg(dev,
@@ -2585,6 +2635,7 @@ static void wa_buf_in_cb(struct urb *urb)
        case -ENOENT:           /* as it was done by the who unlinked us */
                break;
        default:                /* Other errors ... */
+               resubmit_dti = 1;
                spin_lock_irqsave(&xfer->lock, flags);
                rpipe = xfer->ep->hcpriv;
                if (printk_ratelimit())
@@ -2607,13 +2658,8 @@ static void wa_buf_in_cb(struct urb *urb)
                if (rpipe_ready)
                        wa_xfer_delayed_run(rpipe);
        }
-       /*
-        * If we are in this callback and isoc_data_frame_count > 0, it means
-        * that the dti_urb submission was delayed in wa_dti_cb.  Once
-        * isoc_data_frame_count gets to 1, we can submit the deferred URB
-        * since the last buf_in_urb was just submitted.
-        */
-       if (isoc_data_frame_count == 1) {
+
+       if (resubmit_dti) {
                int result = usb_submit_urb(wa->dti_urb, GFP_ATOMIC);
                if (result < 0) {
                        dev_err(dev, "DTI Error: Could not submit DTI URB (%d)\n",