Transfer requests for usb disks can contain a large number of 4k fragments.
Assume that it doesn't matter if there are LINK TRB in fragment lists
that are 1k aligned.
This should stop errors when transfer requests for usb disks contain
more fragments that will fit in a ring segment.
Signed-off-by: David Laight <david.laight@xxxxxxxxxx>
---
Note that this patch just allows large numbers of aligned fragments for
bulk scatter-gather transfers.
It doesn't remove the need for the patch that changes the way the ownership
of the the first TRB is set in order to avoid the controller seeing 'dangling'
LINK TRBs.
However it does reduce the likelyhood of dangling LINK TRBs, so might seem to
make the other patch unnecessary.
I've only compile tested it - but it should be fine.
drivers/usb/host/xhci-ring.c | 49 ++++++++++++++++++++++++++++++++++----------
1 file changed, 38 insertions(+), 11 deletions(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index a0b248c..7a4efd2 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2932,7 +2932,8 @@ static void queue_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
* FIXME allocate segments if the ring is full.
*/
static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
- u32 ep_state, unsigned int num_trbs, gfp_t mem_flags)
+ u32 ep_state, unsigned int num_trbs, gfp_t mem_flags,
+ bool aligned_xfer)
{
unsigned int num_trbs_needed;
@@ -2980,6 +2981,9 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
* Simplest solution is to fill the trb before the
* LINK with nop commands.
*/
+ if (aligned_xfer)
+ /* Caller says buffer is aligned */
+ break;
if (num_trbs == 1 || num_trbs <= usable || usable == 0)
break;
@@ -3073,7 +3077,8 @@ static int prepare_transfer(struct xhci_hcd *xhci,
unsigned int num_trbs,
struct urb *urb,
unsigned int td_index,
- gfp_t mem_flags)
+ gfp_t mem_flags,
+ bool aligned_xfer)
{
int ret;
struct urb_priv *urb_priv;
@@ -3090,7 +3095,7 @@ static int prepare_transfer(struct xhci_hcd *xhci,
ret = prepare_ring(xhci, ep_ring,
le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK,
- num_trbs, mem_flags);
+ num_trbs, mem_flags, aligned_xfer);
if (ret)
return ret;
@@ -3117,7 +3122,8 @@ static int prepare_transfer(struct xhci_hcd *xhci,
return 0;
}
-static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb)
+static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb,
+ bool *aligned_xfer)
{
int num_sgs, num_trbs, running_total, temp, i;
struct scatterlist *sg;
@@ -3125,11 +3131,30 @@ static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb)
sg = NULL;
num_sgs = urb->num_mapped_sgs;
temp = urb->transfer_buffer_length;
+ *aligned_xfer = true;
num_trbs = 0;
for_each_sg(urb->sg, sg, num_sgs, i) {
unsigned int len = sg_dma_len(sg);
+ /*
+ * The 1.0 spec says LINK TRB are only allowed at data offsets
+ * that are multiples of the transfer burst size.
+ * While the burst size might be 16k the effect is probably
+ * that the transfer is split. In particular a non-full-length
+ * data block might be sent - terminating a bulk transfer.
+ *
+ * prepare_ring() ensures that the data TRB don't cross a LINK,
+ * but for usb disks we see large numbers of fragments of 4k
+ * and that exceeds the size of each ring segment.
+ *
+ * If all the fragments start and end on 1k boundaries tell
+ * prepare_ring() not to worry about LINK TRB.
+ */
+ if ((sg_dma_address(sg) | sg_dma_len(sg)) & 1023)
+ /* Fragment not 1k aligned */
+ *aligned_xfer = false;
+
/* Scatter gather list entries may cross 64KB boundaries */
running_total = TRB_MAX_BUFF_SIZE -
(sg_dma_address(sg) & (TRB_MAX_BUFF_SIZE - 1));
@@ -3284,6 +3309,7 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
bool first_trb;
u64 addr;
bool more_trbs_coming;
+ bool aligned_xfer;
struct xhci_generic_trb *start_trb;
int start_cycle;
@@ -3292,14 +3318,14 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
if (!ep_ring)
return -EINVAL;
- num_trbs = count_sg_trbs_needed(xhci, urb);
+ num_trbs = count_sg_trbs_needed(xhci, urb, &aligned_xfer);
num_sgs = urb->num_mapped_sgs;
total_packet_count = DIV_ROUND_UP(urb->transfer_buffer_length,
usb_endpoint_maxp(&urb->ep->desc));
trb_buff_len = prepare_transfer(xhci, xhci->devs[slot_id],
ep_index, urb->stream_id,
- num_trbs, urb, 0, mem_flags);
+ num_trbs, urb, 0, mem_flags, aligned_xfer);
if (trb_buff_len < 0)
return trb_buff_len;
@@ -3470,7 +3496,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
ret = prepare_transfer(xhci, xhci->devs[slot_id],
ep_index, urb->stream_id,
- num_trbs, urb, 0, mem_flags);
+ num_trbs, urb, 0, mem_flags, false);
if (ret < 0)
return ret;
@@ -3600,7 +3626,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
num_trbs++;
ret = prepare_transfer(xhci, xhci->devs[slot_id],
ep_index, urb->stream_id,
- num_trbs, urb, 0, mem_flags);
+ num_trbs, urb, 0, mem_flags, false);
if (ret < 0)
return ret;
@@ -3810,7 +3836,8 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
trbs_per_td = count_isoc_trbs_needed(xhci, urb, i);
ret = prepare_transfer(xhci, xhci->devs[slot_id], ep_index,
- urb->stream_id, trbs_per_td, urb, i, mem_flags);
+ urb->stream_id, trbs_per_td, urb, i, mem_flags,
+ false);
if (ret < 0) {
if (i == 0)
return ret;
@@ -3969,7 +3996,7 @@ int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
* Do not insert any td of the urb to the ring if the check failed.
*/
ret = prepare_ring(xhci, ep_ring, le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK,
- num_trbs, mem_flags);
+ num_trbs, mem_flags, false);
if (ret)
return ret;
@@ -4026,7 +4053,7 @@ static int queue_command(struct xhci_hcd *xhci, u32 field1, u32 field2,
reserved_trbs++;
ret = prepare_ring(xhci, xhci->cmd_ring, EP_STATE_RUNNING,
- reserved_trbs, GFP_ATOMIC);
+ reserved_trbs, GFP_ATOMIC, false);
if (ret < 0) {
xhci_err(xhci, "ERR: No room for command on command ring\n");
if (command_must_succeed)
--
1.8.1.2
--
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