On 15/07/16 14:13, Tvrtko Ursulin wrote:
On 29/06/16 17:00, Chris Wilson wrote:
On Wed, Jun 29, 2016 at 04:41:58PM +0100, Tvrtko Ursulin wrote:
On 29/06/16 16:34, Chris Wilson wrote:
On Wed, Jun 29, 2016 at 04:09:31PM +0100, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Replace per-engine initialization with a common half-programatic,
half-data driven code for ease of maintenance and compactness.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
This is the biggest pill to swallow (since our 5x5 table is only
sparsely populated), but it looks correct, and more importantly
easier to
read.
Yeah I was out of ideas on how to improve it. Fresh mind needed to
try and spot a pattern in how MI_SEMAPHORE_SYNC_* and GEN6_*SYNC map
to bits and registers respectively, and write it as a function.
It's actually a very simple cyclic function based on register
offset = base + (signaler hw_id - waiter hw_id - 1) % num_rings.
(The only real challenge is picking the direction.)
commit c8c99b0f0dea1ced5d0e10cdb9143356cc16b484
Author: Ben Widawsky <ben@xxxxxxxxxxxx>
Date: Wed Sep 14 20:32:47 2011 -0700
drm/i915: Dumb down the semaphore logic
While I think the previous code is correct, it was hard to follow
and
hard to debug. Since we already have a ring abstraction, might as
well
use it to handle the semaphore updates and compares.
Doesn't seem to fit, or I just can't figure it out. Needs two functions
to get rid of the table:
f1(0, 1) = 2
f1(0, 2) = 0
f1(0, 3) = 2
f1(1, 0) = 0
f1(1, 2) = 2
f1(1, 3) = 1
f1(2, 0) = 2
f1(2, 1) = 0
f1(2, 3) = 0
f1(3, 0) = 1
f1(3, 1) = 1
f1(3, 2) = 1
and:
f2(0, 1) = 1
f2(0, 2) = 0
f2(0, 3) = 1
f2(1, 0) = 0
f2(1, 2) = 1
f2(1, 3) = 2
f2(2, 0) = 1
f2(2, 1) = 0
f2(2, 3) = 0
f2(3, 0) = 2
f2(3, 1) = 2
f2(3, 2) = 2
A weekend math puzzle for someone? :)
Regards,
Tvrtko
Here's the APL expression for (the transpose of) f2, with -1's filled in
along the leading diagonal (you need ⎕io←0 so the ⍳-vectors are in origin 0)
{¯1+(⍵≠⍳4)⍀(2|⍵)⌽(⌽⍣(1=⍵))1+⍳3}¨⍳4
┌────────┬────────┬────────┬────────┐
│¯1 0 1 2│1 ¯1 0 2│0 1 ¯1 2│1 2 0 ¯1│
└────────┴────────┴────────┴────────┘
or transposed back so that the first argument is the row index and the
second is the column index:
⍉↑{¯1+(⍵≠⍳4)⍀(2|⍵)⌽(⌽⍣(1=⍵))1+⍳3}¨⍳4
¯1 1 0 1
0 ¯1 1 2
1 0 ¯1 0
2 2 2 ¯1
http://tryapl.org/?a=%u2349%u2191%7B%AF1+%28%u2375%u2260%u23734%29%u2340%282%7C%u2375%29%u233D%28%u233D%u2363%281%3D%u2375%29%291+%u23733%7D%A8%u23734&run
f1 is trivially derived from this by the observation that f1 is just f2
with the 1's and 2's interchanged.
.Dave.
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