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firewire: ohci: optimize find_branch_descriptor()

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When z==2, the condition "key == 2" is superfluous because it cannot
occur without "b == 3", as a descriptor with b!=3 and key==2 would be
an OUTPUT_MORE_IMMEDIATE descriptor which cannot be used alone.

Also remove magic numbers and needless computations on the b field.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Clemens Ladisch 2011-04-12 07:54:59 +02:00 committed by Stefan Richter
parent da28947e7e
commit 0ff8fbc617
1 changed files with 3 additions and 4 deletions
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7
drivers/firewire/ohci.c
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@ -1006,13 +1006,12 @@ static void ar_context_run(struct ar_context *ctx)
static struct descriptor *find_branch_descriptor(struct descriptor *d, int z)
{
int b, key;
__le16 branch;
b = (le16_to_cpu(d->control) & DESCRIPTOR_BRANCH_ALWAYS) >> 2;
key = (le16_to_cpu(d->control) & DESCRIPTOR_KEY_IMMEDIATE) >> 8;
branch = d->control & cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS);
/* figure out which descriptor the branch address goes in */
if (z == 2 && (b == 3 || key == 2))
if (z == 2 && branch == cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS))
return d;
else
return d + z - 1;