diff mbox series

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

Message ID 52dbcdfd15d804f35ba8c984c650144782f762da.1600213517.git.robin.murphy@arm.com
State New, archived
Headers show
Series drm: panfrost: Coherency support | expand

Commit Message

Robin Murphy Sept. 15, 2020, 11:51 p.m. UTC
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 <robin.murphy@arm.com>
---
 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(+)

Comments

Steven Price Sept. 17, 2020, 10:37 a.m. UTC | #1
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 <robin.murphy@arm.com>

LGTM

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
>   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,
>   	};
>
diff mbox series

Patch

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,
 	};