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Commit 8af29ccd authored by Francisco Jerez's avatar Francisco Jerez Committed by Ben Skeggs
Browse files

drm/nv50: Fix large 3D performance regression caused by the interchannel sync patches. 



Reported-by: default avatarChristoph Bumiller <e0425955@student.tuwien.ac.at>
Signed-off-by: default avatarFrancisco Jerez <currojerez@riseup.net>
Tested-by: default avatarMaarten Maathuis <madman2003@gmail.com>
Tested-by: default avatarXavier Chantry <chantry.xavier@gmail.com>
Tested-by: default avatarBen Skeggs <bskeggs@redhat.com>
Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
parent 64798817

drivers/gpu/drm/nouveau/nouveau_drv.h

+1 −0
Original line number Diff line number Diff line
@@ -1473,6 +1473,7 @@ nv_match_device(struct drm_device *dev, unsigned device, 
#define NV_SW_SEMAPHORE_OFFSET                                       0x00000064

#define NV_SW_SEMAPHORE_ACQUIRE                                      0x00000068

#define NV_SW_SEMAPHORE_RELEASE                                      0x0000006c

#define NV_SW_YIELD                                                  0x00000080

#define NV_SW_DMA_VBLSEM                                             0x0000018c

#define NV_SW_VBLSEM_OFFSET                                          0x00000400

#define NV_SW_VBLSEM_RELEASE_VALUE                                   0x00000404

drivers/gpu/drm/nouveau/nouveau_fence.c

+39 −7
Original line number Diff line number Diff line
@@ -308,21 +308,54 @@ emit_semaphore(struct nouveau_channel *chan, int method, 
{

	struct drm_nouveau_private *dev_priv = sema->dev->dev_private;

	struct nouveau_fence *fence;

	bool smart = (dev_priv->card_type >= NV_50);

	int ret;



	ret = RING_SPACE(chan, dev_priv->card_type >= NV_50 ? 6 : 4);

	ret = RING_SPACE(chan, smart ? 8 : 4);

	if (ret)

		return ret;



	if (dev_priv->card_type >= NV_50) {

	if (smart) {

		BEGIN_RING(chan, NvSubSw, NV_SW_DMA_SEMAPHORE, 1);

		OUT_RING(chan, NvSema);

	}

	BEGIN_RING(chan, NvSubSw, NV_SW_SEMAPHORE_OFFSET, 1);

	OUT_RING(chan, sema->mem->start);



	if (smart && method == NV_SW_SEMAPHORE_ACQUIRE) {

		/*

		 * NV50 tries to be too smart and context-switch

		 * between semaphores instead of doing a "first come,

		 * first served" strategy like previous cards

		 * do.

		 *

		 * That's bad because the ACQUIRE latency can get as

		 * large as the PFIFO context time slice in the

		 * typical DRI2 case where you have several

		 * outstanding semaphores at the same moment.

		 *

		 * If we're going to ACQUIRE, force the card to

		 * context switch before, just in case the matching

		 * RELEASE is already scheduled to be executed in

		 * another channel.

		 */

		BEGIN_RING(chan, NvSubSw, NV_SW_YIELD, 1);

		OUT_RING(chan, 0);

	}



	BEGIN_RING(chan, NvSubSw, method, 1);

	OUT_RING(chan, 1);



	if (smart && method == NV_SW_SEMAPHORE_RELEASE) {

		/*

		 * Force the card to context switch, there may be

		 * another channel waiting for the semaphore we just

		 * released.

		 */

		BEGIN_RING(chan, NvSubSw, NV_SW_YIELD, 1);

		OUT_RING(chan, 0);

	}



	/* Delay semaphore destruction until its work is done */

	ret = nouveau_fence_new(chan, &fence, true);

	if (ret)
@@ -355,14 +388,13 @@ nouveau_fence_sync(struct nouveau_fence *fence, 
		return nouveau_fence_wait(fence, NULL, false, false);

	}



	/* Signal the semaphore from chan */

	ret = emit_semaphore(chan, NV_SW_SEMAPHORE_RELEASE, sema);

	if (ret)

		goto out;



	/* Make wchan wait until it gets signalled */

	ret = emit_semaphore(wchan, NV_SW_SEMAPHORE_ACQUIRE, sema);

	if (ret)

		goto out;



	/* Signal the semaphore from chan */

	ret = emit_semaphore(chan, NV_SW_SEMAPHORE_RELEASE, sema);

out:

	kref_put(&sema->ref, free_semaphore);

	return ret;