[PATCH] drm/nv50/gr: make ctxprog decide at run time to disable or not xfer

[Martin Peres]

This commit is a follow-up on "drm/nv50/gr: enable ctxprog xfer only when we need it to save power".

The current situation is that some cards (nv92) have an hw regression that lower performance that
has been reported to about 15%.

This commit is the initial work to get the best of both world, that is to say:
- Performance when it is actually needed
- Power consumption when current performance is enough for the current needs

How-to:
- To go for performance      : nvapoke 400830 1
- To go for power consumption: nvapoke 400830 0

Then, force the card to do a context switch (switch to a TTY for instance).
Make sure it worked by peeking 400824. Bit 0x4000 is the XFER_ENABLE.

Reported-by: Marcin Slusarz <marcin.slusarz at gmail.com>
Signed-off-by: Martin Peres <martin.peres at labri.fr>
---
 drivers/gpu/drm/nouveau/nv50_grctx.c |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nv50_grctx.c b/drivers/gpu/drm/nouveau/nv50_grctx.c
index 4b46d69..b2fdb7d 100644
--- a/drivers/gpu/drm/nouveau/nv50_grctx.c
+++ b/drivers/gpu/drm/nouveau/nv50_grctx.c
@@ -74,6 +74,11 @@
 #define CP_FLAG_INTR_NOT_PENDING      0
 #define CP_FLAG_INTR_PENDING          1
 
+/* CTXCTL_FLAGS_3: should only be written by host ! */
+#define CP_FLAG_PM_XFER               ((3 * 32) + 0)
+#define CP_FLAG_PM_XFER_ENABLE        0
+#define CP_FLAG_PM_XFER_DISABLE       1
+
 #define CP_CTX                   0x00100000
 #define CP_CTX_COUNT             0x000f0000
 #define CP_CTX_COUNT_SHIFT               16
@@ -163,6 +168,7 @@ enum cp_label {
 	cp_setup_save,
 	cp_swap_state,
 	cp_prepare_exit,
+	cp_xfer,
 	cp_exit,
 };
 
@@ -263,13 +269,17 @@ nv50_grctx_init(struct nouveau_grctx *ctx)
 	cp_set (ctx, UNK03, CLEAR);
 	cp_set (ctx, UNK1D, CLEAR);
 
-	cp_bra (ctx, USER_SAVE, PENDING, cp_exit);
+	cp_bra (ctx, USER_SAVE, PENDING, cp_xfer);
 	cp_out (ctx, CP_NEXT_TO_CURRENT);
 
+	/* disable xfer unless we are told otherwise by the host */
+	cp_name(ctx, cp_xfer);
+	cp_bra (ctx, PM_XFER, DISABLE, cp_exit);
+	cp_set (ctx, XFER_SWITCH, DISABLE);
+
 	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 */
-- 
1.7.8.3


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