f30e6d3e41
We do not need slab allocations anymore in order to satisfy
streaming DMA mapping constraints, thanks to commit da28947e7e
"firewire: ohci: avoid separate DMA mapping for small AT payloads".
(Besides, the slab-allocated buffers that firewire-core, firewire-sbp2,
and firedtv used to provide for 8-byte write and lock requests were
still not fully portable since they crossed cacheline boundaries or
shared a cacheline with unrelated CPU-accessed data. snd-firewire-lib
got this aspect right by using an extra kmalloc/ kfree just for the
8-byte transaction buffer.)
This change replaces kmalloc'ed lock transaction scratch buffers in
firewire-core, firedtv, and snd-firewire-lib by local stack allocations.
Perhaps the most notable result of the change is simpler locking because
there is no need to serialize usages of preallocated per-device buffers
anymore. Also, allocations and deallocations are simpler.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
38 lines
1.2 KiB
C
38 lines
1.2 KiB
C
#ifndef SOUND_FIREWIRE_ISO_RESOURCES_H_INCLUDED
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#define SOUND_FIREWIRE_ISO_RESOURCES_H_INCLUDED
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#include <linux/mutex.h>
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#include <linux/types.h>
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struct fw_unit;
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/**
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* struct fw_iso_resources - manages channel/bandwidth allocation
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* @channels_mask: if the device does not support all channel numbers, set this
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* bit mask to something else than the default (all ones)
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*
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* This structure manages (de)allocation of isochronous resources (channel and
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* bandwidth) for one isochronous stream.
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*/
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struct fw_iso_resources {
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u64 channels_mask;
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/* private: */
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struct fw_unit *unit;
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struct mutex mutex;
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unsigned int channel;
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unsigned int bandwidth; /* in bandwidth units, without overhead */
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unsigned int bandwidth_overhead;
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int generation; /* in which allocation is valid */
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bool allocated;
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};
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int fw_iso_resources_init(struct fw_iso_resources *r,
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struct fw_unit *unit);
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void fw_iso_resources_destroy(struct fw_iso_resources *r);
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int fw_iso_resources_allocate(struct fw_iso_resources *r,
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unsigned int max_payload_bytes, int speed);
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int fw_iso_resources_update(struct fw_iso_resources *r);
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void fw_iso_resources_free(struct fw_iso_resources *r);
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#endif
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