Re: [PATCH 2/3] drm/panfrost: Support cache-coherent integrations

2020-09-17 Thread Steven Price 

On 16/09/2020 00:51, Robin Murphy wrote:

When the GPU's ACE-Lite interface is fully wired up and capable of
snooping CPU caches, it may be described as "dma-coherent" in
devicetree, which will already inform the DMA layer not to perform
unnecessary cache maintenance. However, we still need to ensure that
the GPU uses the appropriate cacheable outer-shareable attributes in
order to generate the requisite snoop signals, and that CPU mappings
don't create a mismatch by using a non-cacheable type either.

Signed-off-by: Robin Murphy 


LGTM

Reviewed-by: Steven Price 


---
  drivers/gpu/drm/panfrost/panfrost_device.h | 1 +
  drivers/gpu/drm/panfrost/panfrost_drv.c| 2 ++
  drivers/gpu/drm/panfrost/panfrost_gem.c| 2 ++
  drivers/gpu/drm/panfrost/panfrost_mmu.c| 1 +
  4 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h 
b/drivers/gpu/drm/panfrost/panfrost_device.h
index c30c719a8059..b31f45315e96 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -84,6 +84,7 @@ struct panfrost_device {
/* pm_domains for devices with more than one. */
struct device *pm_domain_devs[MAX_PM_DOMAINS];
struct device_link *pm_domain_links[MAX_PM_DOMAINS];
+   bool coherent;
  
  	struct panfrost_features features;

const struct panfrost_compatible *comp;
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c 
b/drivers/gpu/drm/panfrost/panfrost_drv.c
index ada51df9a7a3..2a6f2f716b2f 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -588,6 +588,8 @@ static int panfrost_probe(struct platform_device *pdev)
if (!pfdev->comp)
return -ENODEV;
  
+	pfdev->coherent = device_get_dma_attr(&pdev->dev) == DEV_DMA_COHERENT;

+
/* Allocate and initialze the DRM device. */
ddev = drm_dev_alloc(&panfrost_drm_driver, &pdev->dev);
if (IS_ERR(ddev))
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c 
b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 33355dd302f1..cdf1a8754eba 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -220,6 +220,7 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs 
= {
   */
  struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, 
size_t size)
  {
+   struct panfrost_device *pfdev = dev->dev_private;
struct panfrost_gem_object *obj;
  
  	obj = kzalloc(sizeof(*obj), GFP_KERNEL);

@@ -229,6 +230,7 @@ struct drm_gem_object *panfrost_gem_create_object(struct 
drm_device *dev, size_t
INIT_LIST_HEAD(&obj->mappings.list);
mutex_init(&obj->mappings.lock);
obj->base.base.funcs = &panfrost_gem_funcs;
+   obj->base.map_cached = pfdev->coherent;
  
  	return &obj->base.base;

  }
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c 
b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index e8f7b11352d2..8852fd378f7a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -371,6 +371,7 @@ int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv 
*priv)
.pgsize_bitmap  = SZ_4K | SZ_2M,
.ias= FIELD_GET(0xff, pfdev->features.mmu_features),
.oas= FIELD_GET(0xff00, 
pfdev->features.mmu_features),
+   .coherent_walk  = pfdev->coherent,
.tlb= &mmu_tlb_ops,
.iommu_dev  = pfdev->dev,
};



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[PATCH 2/3] drm/panfrost: Support cache-coherent integrations

2020-09-15 Thread Robin Murphy 
When the GPU's ACE-Lite interface is fully wired up and capable of
snooping CPU caches, it may be described as "dma-coherent" in
devicetree, which will already inform the DMA layer not to perform
unnecessary cache maintenance. However, we still need to ensure that
the GPU uses the appropriate cacheable outer-shareable attributes in
order to generate the requisite snoop signals, and that CPU mappings
don't create a mismatch by using a non-cacheable type either.

Signed-off-by: Robin Murphy 
---
 drivers/gpu/drm/panfrost/panfrost_device.h | 1 +
 drivers/gpu/drm/panfrost/panfrost_drv.c| 2 ++
 drivers/gpu/drm/panfrost/panfrost_gem.c| 2 ++
 drivers/gpu/drm/panfrost/panfrost_mmu.c| 1 +
 4 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h 
b/drivers/gpu/drm/panfrost/panfrost_device.h
index c30c719a8059..b31f45315e96 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -84,6 +84,7 @@ struct panfrost_device {
/* pm_domains for devices with more than one. */
struct device *pm_domain_devs[MAX_PM_DOMAINS];
struct device_link *pm_domain_links[MAX_PM_DOMAINS];
+   bool coherent;
 
struct panfrost_features features;
const struct panfrost_compatible *comp;
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c 
b/drivers/gpu/drm/panfrost/panfrost_drv.c
index ada51df9a7a3..2a6f2f716b2f 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -588,6 +588,8 @@ static int panfrost_probe(struct platform_device *pdev)
if (!pfdev->comp)
return -ENODEV;
 
+   pfdev->coherent = device_get_dma_attr(&pdev->dev) == DEV_DMA_COHERENT;
+
/* Allocate and initialze the DRM device. */
ddev = drm_dev_alloc(&panfrost_drm_driver, &pdev->dev);
if (IS_ERR(ddev))
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c 
b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 33355dd302f1..cdf1a8754eba 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -220,6 +220,7 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs 
= {
  */
 struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, 
size_t size)
 {
+   struct panfrost_device *pfdev = dev->dev_private;
struct panfrost_gem_object *obj;
 
obj = kzalloc(sizeof(*obj), GFP_KERNEL);
@@ -229,6 +230,7 @@ struct drm_gem_object *panfrost_gem_create_object(struct 
drm_device *dev, size_t
INIT_LIST_HEAD(&obj->mappings.list);
mutex_init(&obj->mappings.lock);
obj->base.base.funcs = &panfrost_gem_funcs;
+   obj->base.map_cached = pfdev->coherent;
 
return &obj->base.base;
 }
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c 
b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index e8f7b11352d2..8852fd378f7a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -371,6 +371,7 @@ int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv 
*priv)
.pgsize_bitmap  = SZ_4K | SZ_2M,
.ias= FIELD_GET(0xff, pfdev->features.mmu_features),
.oas= FIELD_GET(0xff00, 
pfdev->features.mmu_features),
+   .coherent_walk  = pfdev->coherent,
.tlb= &mmu_tlb_ops,
.iommu_dev  = pfdev->dev,
};
-- 
2.28.0.dirty

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