From f30e6d3e419bfb5540fa82ba7eca01d578556e6b Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Fri, 22 Apr 2011 15:13:54 +0200 Subject: 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 Acked-by: Clemens Ladisch --- drivers/media/dvb/firewire/firedtv-avc.c | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-) (limited to 'drivers/media') 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; } -- cgit v1.2.1