Re: [PATCH v2 4/8] drm/etnaviv: replace MMU flush marker with flush sequence

On Fri, 2019-07-05 at 19:17 +0200, Lucas Stach wrote:

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@pengutronix.de

drivers/gpu/drm/etnaviv/etnaviv_buffer.c | 9 +++++---- drivers/gpu/drm/etnaviv/etnaviv_gpu.h | 1 + drivers/gpu/drm/etnaviv/etnaviv_mmu.c | 6 +++--- drivers/gpu/drm/etnaviv/etnaviv_mmu.h | 2 +- 4 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c index 6400a88cd778..532db77624da 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c @@ -315,6 +315,7 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state, u32 return_target, return_dwords; u32 link_target, link_dwords; bool switch_context = gpu->exec_state != exec_state;

• bool need_flush = gpu->flush_seq != gpu->mmu->flush_seq;

Can gpu->mmu->flush_seq change between here ...

lockdep_assert_held(&gpu->lock);

@@ -329,14 +330,14 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state, * 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 || switch_context) {

• if (need_flush || 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
  

@@ -349,7 +350,7 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,

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,
  

@@ -369,7 +370,7 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state, SYNC_RECIPIENT_PE); }

• 	gpu->mmu->need_flush = false;
  

• 	gpu->flush_seq = gpu->mmu->flush_seq;
  

... and here? If so, gpu->flush_seq should be set to the value that gpu->mmu->flush_seq had when need_flush was determined.

}

if (switch_context) {

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h index 933c8d016f11..96380942cd8c 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h @@ -137,6 +137,7 @@ struct etnaviv_gpu { int irq;

struct etnaviv_iommu *mmu;

• unsigned int flush_seq;

  /* Power Control: */ struct clk *clk_bus;

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c index dd81376724d7..3348d9962177 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c @@ -263,7 +263,7 @@ int etnaviv_iommu_map_gem(struct etnaviv_iommu *mmu, }

list_add_tail(&mapping->mmu_node, &mmu->mappings);

• mmu->need_flush = true;

• mmu->flush_seq++;

unlock: mutex_unlock(&mmu->lock);

@@ -282,7 +282,7 @@ void etnaviv_iommu_unmap_gem(struct etnaviv_iommu *mmu, etnaviv_iommu_remove_mapping(mmu, mapping);

list_del(&mapping->mmu_node);

• mmu->need_flush = true;

• mmu->flush_seq++; mutex_unlock(&mmu->lock);

}

@@ -371,7 +371,7 @@ int etnaviv_iommu_get_suballoc_va(struct etnaviv_iommu *mmu, }

list_add_tail(&mapping->mmu_node, &mmu->mappings);

• mmu->need_flush = true;
  

• mmu->flush_seq++;
  

  }

  mapping->use = 1;

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_mmu.h b/drivers/gpu/drm/etnaviv/etnaviv_mmu.h index fe1c9d6b9334..34afe25df9ca 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.h +++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.h @@ -48,7 +48,7 @@ struct etnaviv_iommu { struct mutex lock; struct list_head mappings; struct drm_mm mm;

• bool need_flush;

• unsigned int flush_seq;

};

struct etnaviv_gem_object;

regards Philipp