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.
Reviewed-by: Steven Price steven.price@arm.com Tested-by: Neil Armstrong narmstrong@baylibre.com 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(+)
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, };