122 lines
4.4 KiB
Diff
122 lines
4.4 KiB
Diff
From: Ben Hutchings <ben@decadent.org.uk>
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Date: Sat, 1 Feb 2014 16:36:56 +0100
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Subject: xhci: Revert generalised sg support
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Bug-Debian: http://bugs.debian.org/733826
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Bug-Debian: http://bugs.debian.org/736274
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Revert part of "USB: introduce usb_device_no_sg_constraint() helper"
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(commit bcc48f1a7a0d40ae2e5a26aff72c2b674fd8b596),
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"usb: xhci: Link TRB must not occur within a USB payload burst"
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(commit 35773dac5f862cb1c82ea151eba3e2f6de51ec3e),
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"xhci: Avoid infinite loop when sg urb requires too many trbs"
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(commit d6c9ea9069af684358efedcaf2f2f687f51c58ee) and
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"xhci: Set scatter-gather limit to avoid failed block writes."
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(commit f2d9b991c549f159dc9ae81f77d8206c790cbfee).
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The first two have resulted in serious regressions for USB storage,
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apparently not entirely fixed by the last two.
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---
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--- a/drivers/usb/host/xhci-ring.c
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+++ b/drivers/usb/host/xhci-ring.c
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@@ -2973,58 +2973,8 @@ static int prepare_ring(struct xhci_hcd
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}
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while (1) {
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- if (room_on_ring(xhci, ep_ring, num_trbs)) {
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- union xhci_trb *trb = ep_ring->enqueue;
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- unsigned int usable = ep_ring->enq_seg->trbs +
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- TRBS_PER_SEGMENT - 1 - trb;
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- u32 nop_cmd;
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-
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- /*
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- * Section 4.11.7.1 TD Fragments states that a link
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- * TRB must only occur at the boundary between
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- * data bursts (eg 512 bytes for 480M).
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- * While it is possible to split a large fragment
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- * we don't know the size yet.
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- * Simplest solution is to fill the trb before the
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- * LINK with nop commands.
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- */
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- if (num_trbs == 1 || num_trbs <= usable || usable == 0)
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- break;
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-
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- if (ep_ring->type != TYPE_BULK)
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- /*
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- * While isoc transfers might have a buffer that
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- * crosses a 64k boundary it is unlikely.
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- * Since we can't add NOPs without generating
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- * gaps in the traffic just hope it never
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- * happens at the end of the ring.
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- * This could be fixed by writing a LINK TRB
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- * instead of the first NOP - however the
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- * TRB_TYPE_LINK_LE32() calls would all need
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- * changing to check the ring length.
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- */
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- break;
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-
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- if (num_trbs >= TRBS_PER_SEGMENT) {
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- xhci_err(xhci, "Too many fragments %d, max %d\n",
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- num_trbs, TRBS_PER_SEGMENT - 1);
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- return -EINVAL;
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- }
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-
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- nop_cmd = cpu_to_le32(TRB_TYPE(TRB_TR_NOOP) |
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- ep_ring->cycle_state);
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- ep_ring->num_trbs_free -= usable;
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- do {
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- trb->generic.field[0] = 0;
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- trb->generic.field[1] = 0;
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- trb->generic.field[2] = 0;
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- trb->generic.field[3] = nop_cmd;
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- trb++;
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- } while (--usable);
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- ep_ring->enqueue = trb;
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- if (room_on_ring(xhci, ep_ring, num_trbs))
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- break;
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- }
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+ if (room_on_ring(xhci, ep_ring, num_trbs))
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+ break;
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if (ep_ring == xhci->cmd_ring) {
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xhci_err(xhci, "Do not support expand command ring\n");
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--- a/drivers/usb/host/xhci.c
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+++ b/drivers/usb/host/xhci.c
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@@ -4716,11 +4716,12 @@ int xhci_gen_setup(struct usb_hcd *hcd,
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struct device *dev = hcd->self.controller;
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int retval;
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- /* Limit the block layer scatter-gather lists to half a segment. */
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- hcd->self.sg_tablesize = TRBS_PER_SEGMENT / 2;
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+ /* Accept arbitrarily long scatter-gather lists */
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+ hcd->self.sg_tablesize = ~0;
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/* support to build packet from discontinuous buffers */
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- hcd->self.no_sg_constraint = 1;
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+ /* XXX doesn't generally work yet */
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+ hcd->self.no_sg_constraint = 0;
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/* XHCI controllers don't stop the ep queue on short packets :| */
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hcd->self.no_stop_on_short = 1;
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--- a/drivers/usb/host/xhci.h
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+++ b/drivers/usb/host/xhci.h
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@@ -1260,7 +1260,7 @@ union xhci_trb {
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* since the command ring is 64-byte aligned.
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* It must also be greater than 16.
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*/
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-#define TRBS_PER_SEGMENT 256
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+#define TRBS_PER_SEGMENT 64
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/* Allow two commands + a link TRB, along with any reserved command TRBs */
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#define MAX_RSVD_CMD_TRBS (TRBS_PER_SEGMENT - 3)
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#define TRB_SEGMENT_SIZE (TRBS_PER_SEGMENT*16)
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--- a/include/linux/usb.h
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+++ b/include/linux/usb.h
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@@ -1264,8 +1264,6 @@ typedef void (*usb_complete_t)(struct ur
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* @sg: scatter gather buffer list, the buffer size of each element in
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* the list (except the last) must be divisible by the endpoint's
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* max packet size if no_sg_constraint isn't set in 'struct usb_bus'
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- * (FIXME: scatter-gather under xHCI is broken for periodic transfers.
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- * Do not use urb->sg for interrupt endpoints for now, only bulk.)
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* @num_mapped_sgs: (internal) number of mapped sg entries
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* @num_sgs: number of entries in the sg list
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* @transfer_buffer_length: How big is transfer_buffer. The transfer may
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