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drm/nv50/gr: enable ctxprog xfer only when we need it to save power

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This patch adds instructions to ctxprog and by doing, impacts context
switching performance.  My testcase showed a 1% performance cost using
glxgears that is a context-switch bound application.

Please test and report bugs/performance/power/other.

Many thanks to Maxim Levitsky for his dedicated work on lowering power
consumption with nouveau.

More patches are coming thanks to his work:

https://bugs.freedesktop.org/show_bug.cgi?id=37922

Signed-off-by: Martin Peres <martin.peres@ensi-bourges.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This commit is contained in:
Martin Peres 2011-07-30 23:08:45 +02:00 committed by Ben Skeggs
parent c16a3a358b
commit fbba036a56
1 changed files with 5 additions and 0 deletions
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5
drivers/gpu/drm/nouveau/nv50_grctx.c
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@ -40,6 +40,9 @@
#define CP_FLAG_UNK0B ((0 * 32) + 0xb)
#define CP_FLAG_UNK0B_CLEAR 0
#define CP_FLAG_UNK0B_SET 1
#define CP_FLAG_XFER_SWITCH ((0 * 32) + 0xe)
#define CP_FLAG_XFER_SWITCH_DISABLE 0
#define CP_FLAG_XFER_SWITCH_ENABLE 1
#define CP_FLAG_STATE ((0 * 32) + 0x1c)
#define CP_FLAG_STATE_STOPPED 0
#define CP_FLAG_STATE_RUNNING 1
@ -199,6 +202,7 @@ nv50_grctx_init(struct nouveau_grctx *ctx)
}
cp_set (ctx, STATE, RUNNING);
cp_set (ctx, XFER_SWITCH, ENABLE);
/* decide whether we're loading/unloading the context */
cp_bra (ctx, AUTO_SAVE, PENDING, cp_setup_save);
cp_bra (ctx, USER_SAVE, PENDING, cp_setup_save);
@ -265,6 +269,7 @@ nv50_grctx_init(struct nouveau_grctx *ctx)
cp_name(ctx, cp_exit);
cp_set (ctx, USER_SAVE, NOT_PENDING);
cp_set (ctx, USER_LOAD, NOT_PENDING);
cp_set (ctx, XFER_SWITCH, DISABLE);
cp_set (ctx, STATE, STOPPED);
cp_out (ctx, CP_END);
ctx->ctxvals_pos += 0x400; /* padding... no idea why you need it */