kernel-ark/drivers/usb/host/ehci-mem.c
Ming Lei 9118f9eb4f USB: EHCI: improve interrupt qh unlink
ehci-hcd currently unlinks an interrupt QH when it becomes empty, that
is, after its last URB completes.  This works well because in almost
all cases, the completion handler for an interrupt URB resubmits the
URB; therefore the QH doesn't become empty and doesn't get unlinked.

When we start using tasklets for URB completion, this scheme won't work
as well.  The resubmission won't occur until the tasklet runs, which
will be some time after the completion is queued with the tasklet.
During that delay, the QH will be empty and so will be unlinked
unnecessarily.

To prevent this problem, this patch adds a 5-ms time delay before empty
interrupt QHs are unlinked.  Most often, during that time the interrupt
URB will be resubmitted and thus we can avoid unlinking the QH.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-12 11:43:48 -07:00

247 lines
6.5 KiB
C

/*
* Copyright (c) 2001 by David Brownell
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/* this file is part of ehci-hcd.c */
/*-------------------------------------------------------------------------*/
/*
* There's basically three types of memory:
* - data used only by the HCD ... kmalloc is fine
* - async and periodic schedules, shared by HC and HCD ... these
* need to use dma_pool or dma_alloc_coherent
* - driver buffers, read/written by HC ... single shot DMA mapped
*
* There's also "register" data (e.g. PCI or SOC), which is memory mapped.
* No memory seen by this driver is pageable.
*/
/*-------------------------------------------------------------------------*/
/* Allocate the key transfer structures from the previously allocated pool */
static inline void ehci_qtd_init(struct ehci_hcd *ehci, struct ehci_qtd *qtd,
dma_addr_t dma)
{
memset (qtd, 0, sizeof *qtd);
qtd->qtd_dma = dma;
qtd->hw_token = cpu_to_hc32(ehci, QTD_STS_HALT);
qtd->hw_next = EHCI_LIST_END(ehci);
qtd->hw_alt_next = EHCI_LIST_END(ehci);
INIT_LIST_HEAD (&qtd->qtd_list);
}
static struct ehci_qtd *ehci_qtd_alloc (struct ehci_hcd *ehci, gfp_t flags)
{
struct ehci_qtd *qtd;
dma_addr_t dma;
qtd = dma_pool_alloc (ehci->qtd_pool, flags, &dma);
if (qtd != NULL) {
ehci_qtd_init(ehci, qtd, dma);
}
return qtd;
}
static inline void ehci_qtd_free (struct ehci_hcd *ehci, struct ehci_qtd *qtd)
{
dma_pool_free (ehci->qtd_pool, qtd, qtd->qtd_dma);
}
static void qh_destroy(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
/* clean qtds first, and know this is not linked */
if (!list_empty (&qh->qtd_list) || qh->qh_next.ptr) {
ehci_dbg (ehci, "unused qh not empty!\n");
BUG ();
}
if (qh->dummy)
ehci_qtd_free (ehci, qh->dummy);
dma_pool_free(ehci->qh_pool, qh->hw, qh->qh_dma);
kfree(qh);
}
static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, gfp_t flags)
{
struct ehci_qh *qh;
dma_addr_t dma;
qh = kzalloc(sizeof *qh, GFP_ATOMIC);
if (!qh)
goto done;
qh->hw = (struct ehci_qh_hw *)
dma_pool_alloc(ehci->qh_pool, flags, &dma);
if (!qh->hw)
goto fail;
memset(qh->hw, 0, sizeof *qh->hw);
qh->qh_dma = dma;
// INIT_LIST_HEAD (&qh->qh_list);
INIT_LIST_HEAD (&qh->qtd_list);
INIT_LIST_HEAD(&qh->unlink_node);
/* dummy td enables safe urb queuing */
qh->dummy = ehci_qtd_alloc (ehci, flags);
if (qh->dummy == NULL) {
ehci_dbg (ehci, "no dummy td\n");
goto fail1;
}
done:
return qh;
fail1:
dma_pool_free(ehci->qh_pool, qh->hw, qh->qh_dma);
fail:
kfree(qh);
return NULL;
}
/*-------------------------------------------------------------------------*/
/* The queue heads and transfer descriptors are managed from pools tied
* to each of the "per device" structures.
* This is the initialisation and cleanup code.
*/
static void ehci_mem_cleanup (struct ehci_hcd *ehci)
{
if (ehci->async)
qh_destroy(ehci, ehci->async);
ehci->async = NULL;
if (ehci->dummy)
qh_destroy(ehci, ehci->dummy);
ehci->dummy = NULL;
/* DMA consistent memory and pools */
if (ehci->qtd_pool)
dma_pool_destroy (ehci->qtd_pool);
ehci->qtd_pool = NULL;
if (ehci->qh_pool) {
dma_pool_destroy (ehci->qh_pool);
ehci->qh_pool = NULL;
}
if (ehci->itd_pool)
dma_pool_destroy (ehci->itd_pool);
ehci->itd_pool = NULL;
if (ehci->sitd_pool)
dma_pool_destroy (ehci->sitd_pool);
ehci->sitd_pool = NULL;
if (ehci->periodic)
dma_free_coherent (ehci_to_hcd(ehci)->self.controller,
ehci->periodic_size * sizeof (u32),
ehci->periodic, ehci->periodic_dma);
ehci->periodic = NULL;
/* shadow periodic table */
kfree(ehci->pshadow);
ehci->pshadow = NULL;
}
/* remember to add cleanup code (above) if you add anything here */
static int ehci_mem_init (struct ehci_hcd *ehci, gfp_t flags)
{
int i;
/* QTDs for control/bulk/intr transfers */
ehci->qtd_pool = dma_pool_create ("ehci_qtd",
ehci_to_hcd(ehci)->self.controller,
sizeof (struct ehci_qtd),
32 /* byte alignment (for hw parts) */,
4096 /* can't cross 4K */);
if (!ehci->qtd_pool) {
goto fail;
}
/* QHs for control/bulk/intr transfers */
ehci->qh_pool = dma_pool_create ("ehci_qh",
ehci_to_hcd(ehci)->self.controller,
sizeof(struct ehci_qh_hw),
32 /* byte alignment (for hw parts) */,
4096 /* can't cross 4K */);
if (!ehci->qh_pool) {
goto fail;
}
ehci->async = ehci_qh_alloc (ehci, flags);
if (!ehci->async) {
goto fail;
}
/* ITD for high speed ISO transfers */
ehci->itd_pool = dma_pool_create ("ehci_itd",
ehci_to_hcd(ehci)->self.controller,
sizeof (struct ehci_itd),
32 /* byte alignment (for hw parts) */,
4096 /* can't cross 4K */);
if (!ehci->itd_pool) {
goto fail;
}
/* SITD for full/low speed split ISO transfers */
ehci->sitd_pool = dma_pool_create ("ehci_sitd",
ehci_to_hcd(ehci)->self.controller,
sizeof (struct ehci_sitd),
32 /* byte alignment (for hw parts) */,
4096 /* can't cross 4K */);
if (!ehci->sitd_pool) {
goto fail;
}
/* Hardware periodic table */
ehci->periodic = (__le32 *)
dma_alloc_coherent (ehci_to_hcd(ehci)->self.controller,
ehci->periodic_size * sizeof(__le32),
&ehci->periodic_dma, 0);
if (ehci->periodic == NULL) {
goto fail;
}
if (ehci->use_dummy_qh) {
struct ehci_qh_hw *hw;
ehci->dummy = ehci_qh_alloc(ehci, flags);
if (!ehci->dummy)
goto fail;
hw = ehci->dummy->hw;
hw->hw_next = EHCI_LIST_END(ehci);
hw->hw_qtd_next = EHCI_LIST_END(ehci);
hw->hw_alt_next = EHCI_LIST_END(ehci);
hw->hw_token &= ~QTD_STS_ACTIVE;
ehci->dummy->hw = hw;
for (i = 0; i < ehci->periodic_size; i++)
ehci->periodic[i] = ehci->dummy->qh_dma;
} else {
for (i = 0; i < ehci->periodic_size; i++)
ehci->periodic[i] = EHCI_LIST_END(ehci);
}
/* software shadow of hardware table */
ehci->pshadow = kcalloc(ehci->periodic_size, sizeof(void *), flags);
if (ehci->pshadow != NULL)
return 0;
fail:
ehci_dbg (ehci, "couldn't init memory\n");
ehci_mem_cleanup (ehci);
return -ENOMEM;
}