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![Alan Stern](/assets/img/avatar_default.png)
This patch (as1579) adds an hrtimer event to handle deallocation of iTDs and siTDs in ehci-hcd. Because of the frame-oriented approach used by the EHCI periodic schedule, the hardware can continue to access the Transfer Descriptor for isochronous (or split-isochronous) transactions for up to a millisecond after the transaction completes. The iTD (or siTD) must not be reused before then. The strategy currently used involves putting completed iTDs on a list of cached entries and every so often returning them to the endpoint's free list. The new strategy reduces overhead by putting completed iTDs back on the free list immediately, although they are not reused until it is safe to do so. When the isochronous endpoint stops (its queue becomes empty), the iTDs on its free list get moved to a global list, from which they will be deallocated after a minimum of 2 ms. This delay is what the new hrtimer event is for. Overall this may not be a tremendous improvement over the current code, but to me it seems a lot more clear and logical. In addition, it removes the need for each iTD to keep a reference to the ehci_iso_stream it belongs to, since the iTD never needs to be moved back to the stream's free list from the global list. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
245 lines
6.4 KiB
C
245 lines
6.4 KiB
C
/*
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* Copyright (c) 2001 by David Brownell
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/* this file is part of ehci-hcd.c */
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/*-------------------------------------------------------------------------*/
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/*
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* There's basically three types of memory:
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* - data used only by the HCD ... kmalloc is fine
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* - async and periodic schedules, shared by HC and HCD ... these
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* need to use dma_pool or dma_alloc_coherent
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* - driver buffers, read/written by HC ... single shot DMA mapped
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*
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* There's also "register" data (e.g. PCI or SOC), which is memory mapped.
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* No memory seen by this driver is pageable.
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*/
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/*-------------------------------------------------------------------------*/
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/* Allocate the key transfer structures from the previously allocated pool */
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static inline void ehci_qtd_init(struct ehci_hcd *ehci, struct ehci_qtd *qtd,
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dma_addr_t dma)
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{
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memset (qtd, 0, sizeof *qtd);
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qtd->qtd_dma = dma;
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qtd->hw_token = cpu_to_hc32(ehci, QTD_STS_HALT);
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qtd->hw_next = EHCI_LIST_END(ehci);
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qtd->hw_alt_next = EHCI_LIST_END(ehci);
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INIT_LIST_HEAD (&qtd->qtd_list);
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}
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static struct ehci_qtd *ehci_qtd_alloc (struct ehci_hcd *ehci, gfp_t flags)
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{
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struct ehci_qtd *qtd;
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dma_addr_t dma;
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qtd = dma_pool_alloc (ehci->qtd_pool, flags, &dma);
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if (qtd != NULL) {
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ehci_qtd_init(ehci, qtd, dma);
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}
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return qtd;
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}
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static inline void ehci_qtd_free (struct ehci_hcd *ehci, struct ehci_qtd *qtd)
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{
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dma_pool_free (ehci->qtd_pool, qtd, qtd->qtd_dma);
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}
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static void qh_destroy(struct ehci_hcd *ehci, struct ehci_qh *qh)
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{
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/* clean qtds first, and know this is not linked */
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if (!list_empty (&qh->qtd_list) || qh->qh_next.ptr) {
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ehci_dbg (ehci, "unused qh not empty!\n");
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BUG ();
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}
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if (qh->dummy)
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ehci_qtd_free (ehci, qh->dummy);
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dma_pool_free(ehci->qh_pool, qh->hw, qh->qh_dma);
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kfree(qh);
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}
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static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, gfp_t flags)
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{
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struct ehci_qh *qh;
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dma_addr_t dma;
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qh = kzalloc(sizeof *qh, GFP_ATOMIC);
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if (!qh)
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goto done;
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qh->hw = (struct ehci_qh_hw *)
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dma_pool_alloc(ehci->qh_pool, flags, &dma);
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if (!qh->hw)
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goto fail;
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memset(qh->hw, 0, sizeof *qh->hw);
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qh->qh_dma = dma;
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// INIT_LIST_HEAD (&qh->qh_list);
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INIT_LIST_HEAD (&qh->qtd_list);
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/* dummy td enables safe urb queuing */
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qh->dummy = ehci_qtd_alloc (ehci, flags);
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if (qh->dummy == NULL) {
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ehci_dbg (ehci, "no dummy td\n");
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goto fail1;
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}
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done:
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return qh;
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fail1:
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dma_pool_free(ehci->qh_pool, qh->hw, qh->qh_dma);
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fail:
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kfree(qh);
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return NULL;
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}
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/*-------------------------------------------------------------------------*/
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/* The queue heads and transfer descriptors are managed from pools tied
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* to each of the "per device" structures.
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* This is the initialisation and cleanup code.
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*/
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static void ehci_mem_cleanup (struct ehci_hcd *ehci)
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{
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if (ehci->async)
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qh_destroy(ehci, ehci->async);
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ehci->async = NULL;
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if (ehci->dummy)
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qh_destroy(ehci, ehci->dummy);
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ehci->dummy = NULL;
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/* DMA consistent memory and pools */
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if (ehci->qtd_pool)
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dma_pool_destroy (ehci->qtd_pool);
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ehci->qtd_pool = NULL;
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if (ehci->qh_pool) {
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dma_pool_destroy (ehci->qh_pool);
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ehci->qh_pool = NULL;
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}
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if (ehci->itd_pool)
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dma_pool_destroy (ehci->itd_pool);
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ehci->itd_pool = NULL;
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if (ehci->sitd_pool)
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dma_pool_destroy (ehci->sitd_pool);
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ehci->sitd_pool = NULL;
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if (ehci->periodic)
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dma_free_coherent (ehci_to_hcd(ehci)->self.controller,
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ehci->periodic_size * sizeof (u32),
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ehci->periodic, ehci->periodic_dma);
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ehci->periodic = NULL;
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/* shadow periodic table */
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kfree(ehci->pshadow);
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ehci->pshadow = NULL;
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}
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/* remember to add cleanup code (above) if you add anything here */
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static int ehci_mem_init (struct ehci_hcd *ehci, gfp_t flags)
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{
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int i;
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/* QTDs for control/bulk/intr transfers */
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ehci->qtd_pool = dma_pool_create ("ehci_qtd",
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ehci_to_hcd(ehci)->self.controller,
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sizeof (struct ehci_qtd),
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32 /* byte alignment (for hw parts) */,
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4096 /* can't cross 4K */);
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if (!ehci->qtd_pool) {
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goto fail;
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}
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/* QHs for control/bulk/intr transfers */
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ehci->qh_pool = dma_pool_create ("ehci_qh",
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ehci_to_hcd(ehci)->self.controller,
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sizeof(struct ehci_qh_hw),
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32 /* byte alignment (for hw parts) */,
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4096 /* can't cross 4K */);
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if (!ehci->qh_pool) {
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goto fail;
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}
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ehci->async = ehci_qh_alloc (ehci, flags);
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if (!ehci->async) {
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goto fail;
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}
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/* ITD for high speed ISO transfers */
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ehci->itd_pool = dma_pool_create ("ehci_itd",
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ehci_to_hcd(ehci)->self.controller,
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sizeof (struct ehci_itd),
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32 /* byte alignment (for hw parts) */,
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4096 /* can't cross 4K */);
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if (!ehci->itd_pool) {
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goto fail;
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}
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/* SITD for full/low speed split ISO transfers */
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ehci->sitd_pool = dma_pool_create ("ehci_sitd",
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ehci_to_hcd(ehci)->self.controller,
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sizeof (struct ehci_sitd),
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32 /* byte alignment (for hw parts) */,
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4096 /* can't cross 4K */);
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if (!ehci->sitd_pool) {
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goto fail;
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}
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/* Hardware periodic table */
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ehci->periodic = (__le32 *)
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dma_alloc_coherent (ehci_to_hcd(ehci)->self.controller,
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ehci->periodic_size * sizeof(__le32),
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&ehci->periodic_dma, 0);
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if (ehci->periodic == NULL) {
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goto fail;
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}
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if (ehci->use_dummy_qh) {
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struct ehci_qh_hw *hw;
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ehci->dummy = ehci_qh_alloc(ehci, flags);
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if (!ehci->dummy)
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goto fail;
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hw = ehci->dummy->hw;
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hw->hw_next = EHCI_LIST_END(ehci);
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hw->hw_qtd_next = EHCI_LIST_END(ehci);
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hw->hw_alt_next = EHCI_LIST_END(ehci);
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hw->hw_token &= ~QTD_STS_ACTIVE;
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ehci->dummy->hw = hw;
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for (i = 0; i < ehci->periodic_size; i++)
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ehci->periodic[i] = ehci->dummy->qh_dma;
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} else {
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for (i = 0; i < ehci->periodic_size; i++)
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ehci->periodic[i] = EHCI_LIST_END(ehci);
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}
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/* software shadow of hardware table */
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ehci->pshadow = kcalloc(ehci->periodic_size, sizeof(void *), flags);
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if (ehci->pshadow != NULL)
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return 0;
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fail:
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ehci_dbg (ehci, "couldn't init memory\n");
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ehci_mem_cleanup (ehci);
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return -ENOMEM;
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}
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