linux-kernel - [PATCH 4.9 08/32] drm/etnaviv: replace MMU flush marker with flush sequence

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Message-Id: <20200411115419.616038972@linuxfoundation.org>
Date:   Sat, 11 Apr 2020 14:08:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lucas Stach <l.stach@...gutronix.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Guido Günther <agx@...xcpu.org>,
        Robert Beckett <bob.beckett@...labora.com>
Subject: [PATCH 4.9 08/32] drm/etnaviv: replace MMU flush marker with flush sequence

From: Lucas Stach <l.stach@...gutronix.de>

commit 4900dda90af2cb13bc1d4c12ce94b98acc8fe64e upstream.

If a MMU is shared between multiple GPUs, all of them need to flush their
TLBs, so a single marker that gets reset on the first flush won't do.
Replace the flush marker with a sequence number, so that it's possible to
check if the TLB is in sync with the current page table state for each GPU.

Signed-off-by: Lucas Stach <l.stach@...gutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>
Reviewed-by: Guido Günther <agx@...xcpu.org>
Signed-off-by: Robert Beckett <bob.beckett@...labora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/etnaviv/etnaviv_buffer.c |   10 ++++++----
 drivers/gpu/drm/etnaviv/etnaviv_gpu.c    |    2 +-
 drivers/gpu/drm/etnaviv/etnaviv_gpu.h    |    1 +
 drivers/gpu/drm/etnaviv/etnaviv_mmu.c    |    6 +++---
 drivers/gpu/drm/etnaviv/etnaviv_mmu.h    |    2 +-
 5 files changed, 12 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
@@ -257,6 +257,8 @@ void etnaviv_buffer_queue(struct etnaviv
 	unsigned int waitlink_offset = buffer->user_size - 16;
 	u32 return_target, return_dwords;
 	u32 link_target, link_dwords;
+	unsigned int new_flush_seq = READ_ONCE(gpu->mmu->flush_seq);
+	bool need_flush = gpu->flush_seq != new_flush_seq;
 
 	if (drm_debug & DRM_UT_DRIVER)
 		etnaviv_buffer_dump(gpu, buffer, 0, 0x50);
@@ -269,14 +271,14 @@ void etnaviv_buffer_queue(struct etnaviv
 	 * need to append a mmu flush load state, followed by a new
 	 * link to this buffer - a total of four additional words.
 	 */
-	if (gpu->mmu->need_flush || gpu->switch_context) {
+	if (need_flush || gpu->switch_context) {
 		u32 target, extra_dwords;
 
 		/* link command */
 		extra_dwords = 1;
 
 		/* flush command */
-		if (gpu->mmu->need_flush) {
+		if (need_flush) {
 			if (gpu->mmu->version == ETNAVIV_IOMMU_V1)
 				extra_dwords += 1;
 			else
@@ -289,7 +291,7 @@ void etnaviv_buffer_queue(struct etnaviv
 
 		target = etnaviv_buffer_reserve(gpu, buffer, extra_dwords);
 
-		if (gpu->mmu->need_flush) {
+		if (need_flush) {
 			/* Add the MMU flush */
 			if (gpu->mmu->version == ETNAVIV_IOMMU_V1) {
 				CMD_LOAD_STATE(buffer, VIVS_GL_FLUSH_MMU,
@@ -309,7 +311,7 @@ void etnaviv_buffer_queue(struct etnaviv
 					SYNC_RECIPIENT_PE);
 			}
 
-			gpu->mmu->need_flush = false;
+			gpu->flush_seq = new_flush_seq;
 		}
 
 		if (gpu->switch_context) {
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -1313,7 +1313,7 @@ int etnaviv_gpu_submit(struct etnaviv_gp
 	gpu->active_fence = submit->fence;
 
 	if (gpu->lastctx != cmdbuf->ctx) {
-		gpu->mmu->need_flush = true;
+		gpu->mmu->flush_seq++;
 		gpu->switch_context = true;
 		gpu->lastctx = cmdbuf->ctx;
 	}
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
@@ -135,6 +135,7 @@ struct etnaviv_gpu {
 	int irq;
 
 	struct etnaviv_iommu *mmu;
+	unsigned int flush_seq;
 
 	/* Power Control: */
 	struct clk *clk_bus;
--- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
@@ -134,7 +134,7 @@ static int etnaviv_iommu_find_iova(struc
 		 */
 		if (mmu->last_iova) {
 			mmu->last_iova = 0;
-			mmu->need_flush = true;
+			mmu->flush_seq++;
 			continue;
 		}
 
@@ -197,7 +197,7 @@ static int etnaviv_iommu_find_iova(struc
 		 * associated commit requesting this mapping, and retry the
 		 * allocation one more time.
 		 */
-		mmu->need_flush = true;
+		mmu->flush_seq++;
 	}
 
 	return ret;
@@ -354,7 +354,7 @@ u32 etnaviv_iommu_get_cmdbuf_va(struct e
 		 * that the FE MMU prefetch won't load invalid entries.
 		 */
 		mmu->last_iova = buf->vram_node.start + buf->size + SZ_64K;
-		gpu->mmu->need_flush = true;
+		mmu->flush_seq++;
 		mutex_unlock(&mmu->lock);
 
 		return (u32)buf->vram_node.start;
--- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.h
@@ -44,7 +44,7 @@ struct etnaviv_iommu {
 	struct list_head mappings;
 	struct drm_mm mm;
 	u32 last_iova;
-	bool need_flush;
+	unsigned int flush_seq;
 };
 
 struct etnaviv_gem_object;