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Subject[PATCH 5.10 11/57] drm/panfrost: Support cache-coherent integrations
Date
From: Robin Murphy <robin.murphy@arm.com>

commit 268af50f38b1f2199a2e85e38073d7a25c20190c upstream.

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>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/7024ce18c1cb1a226e918037d49175571db0b436.1600780574.git.robin.murphy@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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(+)

--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -88,6 +88,7 @@ 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;
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -587,6 +587,8 @@ static int panfrost_probe(struct platfor
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))
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -218,6 +218,7 @@ static const struct drm_gem_object_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);
@@ -227,6 +228,7 @@ struct drm_gem_object *panfrost_gem_crea
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;
}
--- 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 pa
.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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