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authorStefan Richter2011-04-22 15:13:54 +0200
committerStefan Richter2011-05-10 22:53:44 +0200
commitf30e6d3e419bfb5540fa82ba7eca01d578556e6b (patch)
treee4d6e7bad161a76b09557bf7513358ae1ce8f7fb /drivers/media
parent020abf03cd659388f94cb328e1e1df0656e0d7ff (diff)
firewire: octlet AT payloads can be stack-allocated
We do not need slab allocations anymore in order to satisfy streaming DMA mapping constraints, thanks to commit da28947e7e36 "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>
Diffstat (limited to 'drivers/media')
-rw-r--r--drivers/media/dvb/firewire/firedtv-avc.c15
1 files changed, 1 insertions, 14 deletions
diff --git a/drivers/media/dvb/firewire/firedtv-avc.c b/drivers/media/dvb/firewire/firedtv-avc.c
index fc5ccd8c923a..21c52e3b522e 100644
--- a/drivers/media/dvb/firewire/firedtv-avc.c
+++ b/drivers/media/dvb/firewire/firedtv-avc.c
@@ -1320,14 +1320,10 @@ static int cmp_read(struct firedtv *fdtv, u64 addr, __be32 *data)
{
int ret;
- mutex_lock(&fdtv->avc_mutex);
-
ret = fdtv_read(fdtv, addr, data);
if (ret < 0)
dev_err(fdtv->device, "CMP: read I/O error\n");
- mutex_unlock(&fdtv->avc_mutex);
-
return ret;
}
@@ -1335,18 +1331,9 @@ static int cmp_lock(struct firedtv *fdtv, u64 addr, __be32 data[])
{
int ret;
- mutex_lock(&fdtv->avc_mutex);
-
- /* data[] is stack-allocated and should not be DMA-mapped. */
- memcpy(fdtv->avc_data, data, 8);
-
- ret = fdtv_lock(fdtv, addr, fdtv->avc_data);
+ ret = fdtv_lock(fdtv, addr, data);
if (ret < 0)
dev_err(fdtv->device, "CMP: lock I/O error\n");
- else
- memcpy(data, fdtv->avc_data, 8);
-
- mutex_unlock(&fdtv->avc_mutex);
return ret;
}