[PATCH 2/3] drm/panfrost: Support cache-coherent integrations
Steven Price
steven.price at arm.com
Thu Sep 17 06:37:20 EDT 2020
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 at arm.com>
LGTM
Reviewed-by: Steven Price <steven.price at 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,
> };
>
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