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Subject[PATCH] instmem/gk20a: use DMA API CPU mapping
Date
Commit 69c4938249fb ("drm/nouveau/instmem/gk20a: use direct CPU access")
tried to be smart while using the DMA-API by managing the CPU mappings of
buffers allocated with the DMA-API by itself. In doing so, it relied
on dma_to_phys() which is an architecture-private function not
available everywhere. This broke the build on several architectures.

Since there is no reliable and portable way to obtain the physical
address of a DMA-API buffer, stop trying to be smart and just use the
CPU mapping that the DMA-API can provide. This means that buffers will
be CPU-mapped for all their life as opposed to when we need them, but
anyway using the DMA-API here is a fallback for when no IOMMU is
available so we should not expect optimal behavior.

This makes the IOMMU and DMA-API implementations of instmem diverge
enough that we should maybe put them into separate files...

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
Ben/Dave, since Dave's fix has reached mainline and builds are not
broken anymore, we can proceed one of two ways:

1) Ben merges this for 4.4 and let it flow for -rc2
2) I send another fix against the kernel tree

Which one shall I do?

drm/nouveau/nvkm/subdev/instmem/gk20a.c | 148 +++++++++++++-------------------
lib/include/nvif/os.h | 6 --
2 files changed, 62 insertions(+), 92 deletions(-)

diff --git a/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drm/nouveau/nvkm/subdev/instmem/gk20a.c
index 681b2541229a..4c20fec64d96 100644
--- a/drm/nouveau/nvkm/subdev/instmem/gk20a.c
+++ b/drm/nouveau/nvkm/subdev/instmem/gk20a.c
@@ -56,9 +56,6 @@ struct gk20a_instobj {

/* CPU mapping */
u32 *vaddr;
- struct list_head vaddr_node;
- /* How many clients are using vaddr? */
- u32 use_cpt;
};
#define gk20a_instobj(p) container_of((p), struct gk20a_instobj, memory)

@@ -68,7 +65,6 @@ struct gk20a_instobj {
struct gk20a_instobj_dma {
struct gk20a_instobj base;

- u32 *cpuaddr;
dma_addr_t handle;
struct nvkm_mm_node r;
};
@@ -81,6 +77,11 @@ struct gk20a_instobj_dma {
struct gk20a_instobj_iommu {
struct gk20a_instobj base;

+ /* to link into gk20a_instmem::vaddr_lru */
+ struct list_head vaddr_node;
+ /* how many clients are using vaddr? */
+ u32 use_cpt;
+
/* will point to the higher half of pages */
dma_addr_t *dma_addrs;
/* array of base.mem->size pages (+ dma_addr_ts) */
@@ -109,8 +110,6 @@ struct gk20a_instmem {

/* Only used by DMA API */
struct dma_attrs attrs;
-
- void __iomem * (*cpu_map)(struct nvkm_memory *);
};
#define gk20a_instmem(p) container_of((p), struct gk20a_instmem, base)

@@ -132,46 +131,19 @@ gk20a_instobj_size(struct nvkm_memory *memory)
return (u64)gk20a_instobj(memory)->mem.size << 12;
}

-static void __iomem *
-gk20a_instobj_cpu_map_dma(struct nvkm_memory *memory)
-{
- struct gk20a_instobj_dma *node = gk20a_instobj_dma(memory);
- struct device *dev = node->base.imem->base.subdev.device->dev;
- int npages = nvkm_memory_size(memory) >> 12;
- struct page *pages[npages];
- int i;
-
- /* phys_to_page does not exist on all platforms... */
- pages[0] = pfn_to_page(dma_to_phys(dev, node->handle) >> PAGE_SHIFT);
- for (i = 1; i < npages; i++)
- pages[i] = pages[0] + i;
-
- return vmap(pages, npages, VM_MAP, pgprot_writecombine(PAGE_KERNEL));
-}
-
-static void __iomem *
-gk20a_instobj_cpu_map_iommu(struct nvkm_memory *memory)
-{
- struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
- int npages = nvkm_memory_size(memory) >> 12;
-
- return vmap(node->pages, npages, VM_MAP,
- pgprot_writecombine(PAGE_KERNEL));
-}
-
/*
* Recycle the vaddr of obj. Must be called with gk20a_instmem::lock held.
*/
static void
-gk20a_instobj_recycle_vaddr(struct gk20a_instobj *obj)
+gk20a_instobj_iommu_recycle_vaddr(struct gk20a_instobj_iommu *obj)
{
- struct gk20a_instmem *imem = obj->imem;
+ struct gk20a_instmem *imem = obj->base.imem;
/* there should not be any user left... */
WARN_ON(obj->use_cpt);
list_del(&obj->vaddr_node);
- vunmap(obj->vaddr);
- obj->vaddr = NULL;
- imem->vaddr_use -= nvkm_memory_size(&obj->memory);
+ vunmap(obj->base.vaddr);
+ obj->base.vaddr = NULL;
+ imem->vaddr_use -= nvkm_memory_size(&obj->base.memory);
nvkm_debug(&imem->base.subdev, "vaddr used: %x/%x\n", imem->vaddr_use,
imem->vaddr_max);
}
@@ -187,17 +159,30 @@ gk20a_instmem_vaddr_gc(struct gk20a_instmem *imem, const u64 size)
if (list_empty(&imem->vaddr_lru))
break;

- gk20a_instobj_recycle_vaddr(list_first_entry(&imem->vaddr_lru,
- struct gk20a_instobj, vaddr_node));
+ gk20a_instobj_iommu_recycle_vaddr(
+ list_first_entry(&imem->vaddr_lru,
+ struct gk20a_instobj_iommu, vaddr_node));
}
}

static void __iomem *
-gk20a_instobj_acquire(struct nvkm_memory *memory)
+gk20a_instobj_acquire_dma(struct nvkm_memory *memory)
{
struct gk20a_instobj *node = gk20a_instobj(memory);
struct gk20a_instmem *imem = node->imem;
struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
+
+ nvkm_ltc_flush(ltc);
+
+ return node->vaddr;
+}
+
+static void __iomem *
+gk20a_instobj_acquire_iommu(struct nvkm_memory *memory)
+{
+ struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
+ struct gk20a_instmem *imem = node->base.imem;
+ struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
const u64 size = nvkm_memory_size(memory);
unsigned long flags;

@@ -205,7 +190,7 @@ gk20a_instobj_acquire(struct nvkm_memory *memory)

spin_lock_irqsave(&imem->lock, flags);

- if (node->vaddr) {
+ if (node->base.vaddr) {
if (!node->use_cpt) {
/* remove from LRU list since mapping in use again */
list_del(&node->vaddr_node);
@@ -216,9 +201,10 @@ gk20a_instobj_acquire(struct nvkm_memory *memory)
/* try to free some address space if we reached the limit */
gk20a_instmem_vaddr_gc(imem, size);

- node->vaddr = imem->cpu_map(memory);
-
- if (!node->vaddr) {
+ /* map the pages */
+ node->base.vaddr = vmap(node->pages, size >> PAGE_SHIFT, VM_MAP,
+ pgprot_writecombine(PAGE_KERNEL));
+ if (!node->base.vaddr) {
nvkm_error(&imem->base.subdev, "cannot map instobj - "
"this is not going to end well...\n");
goto out;
@@ -232,15 +218,25 @@ out:
node->use_cpt++;
spin_unlock_irqrestore(&imem->lock, flags);

- return node->vaddr;
+ return node->base.vaddr;
}

static void
-gk20a_instobj_release(struct nvkm_memory *memory)
+gk20a_instobj_release_dma(struct nvkm_memory *memory)
{
struct gk20a_instobj *node = gk20a_instobj(memory);
struct gk20a_instmem *imem = node->imem;
struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
+
+ nvkm_ltc_invalidate(ltc);
+}
+
+static void
+gk20a_instobj_release_iommu(struct nvkm_memory *memory)
+{
+ struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
+ struct gk20a_instmem *imem = node->base.imem;
+ struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
unsigned long flags;

spin_lock_irqsave(&imem->lock, flags);
@@ -284,27 +280,6 @@ gk20a_instobj_map(struct nvkm_memory *memory, struct nvkm_vma *vma, u64 offset)
nvkm_vm_map_at(vma, offset, &node->mem);
}

-/*
- * Clear the CPU mapping of an instobj if it exists
- */
-static void
-gk20a_instobj_dtor(struct gk20a_instobj *node)
-{
- struct gk20a_instmem *imem = node->imem;
- unsigned long flags;
-
- spin_lock_irqsave(&imem->lock, flags);
-
- /* vaddr has already been recycled */
- if (!node->vaddr)
- goto out;
-
- gk20a_instobj_recycle_vaddr(node);
-
-out:
- spin_unlock_irqrestore(&imem->lock, flags);
-}
-
static void *
gk20a_instobj_dtor_dma(struct nvkm_memory *memory)
{
@@ -312,12 +287,10 @@ gk20a_instobj_dtor_dma(struct nvkm_memory *memory)
struct gk20a_instmem *imem = node->base.imem;
struct device *dev = imem->base.subdev.device->dev;

- gk20a_instobj_dtor(&node->base);
-
- if (unlikely(!node->cpuaddr))
+ if (unlikely(!node->base.vaddr))
goto out;

- dma_free_attrs(dev, node->base.mem.size << PAGE_SHIFT, node->cpuaddr,
+ dma_free_attrs(dev, node->base.mem.size << PAGE_SHIFT, node->base.vaddr,
node->handle, &imem->attrs);

out:
@@ -331,13 +304,20 @@ gk20a_instobj_dtor_iommu(struct nvkm_memory *memory)
struct gk20a_instmem *imem = node->base.imem;
struct device *dev = imem->base.subdev.device->dev;
struct nvkm_mm_node *r;
+ unsigned long flags;
int i;

- gk20a_instobj_dtor(&node->base);
-
if (unlikely(list_empty(&node->base.mem.regions)))
goto out;

+ spin_lock_irqsave(&imem->lock, flags);
+
+ /* vaddr has already been recycled */
+ if (node->base.vaddr)
+ gk20a_instobj_iommu_recycle_vaddr(node);
+
+ spin_unlock_irqrestore(&imem->lock, flags);
+
r = list_first_entry(&node->base.mem.regions, struct nvkm_mm_node,
rl_entry);

@@ -368,8 +348,8 @@ gk20a_instobj_func_dma = {
.target = gk20a_instobj_target,
.addr = gk20a_instobj_addr,
.size = gk20a_instobj_size,
- .acquire = gk20a_instobj_acquire,
- .release = gk20a_instobj_release,
+ .acquire = gk20a_instobj_acquire_dma,
+ .release = gk20a_instobj_release_dma,
.rd32 = gk20a_instobj_rd32,
.wr32 = gk20a_instobj_wr32,
.map = gk20a_instobj_map,
@@ -381,8 +361,8 @@ gk20a_instobj_func_iommu = {
.target = gk20a_instobj_target,
.addr = gk20a_instobj_addr,
.size = gk20a_instobj_size,
- .acquire = gk20a_instobj_acquire,
- .release = gk20a_instobj_release,
+ .acquire = gk20a_instobj_acquire_iommu,
+ .release = gk20a_instobj_release_iommu,
.rd32 = gk20a_instobj_rd32,
.wr32 = gk20a_instobj_wr32,
.map = gk20a_instobj_map,
@@ -402,10 +382,10 @@ gk20a_instobj_ctor_dma(struct gk20a_instmem *imem, u32 npages, u32 align,

nvkm_memory_ctor(&gk20a_instobj_func_dma, &node->base.memory);

- node->cpuaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
- &node->handle, GFP_KERNEL,
- &imem->attrs);
- if (!node->cpuaddr) {
+ node->base.vaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
+ &node->handle, GFP_KERNEL,
+ &imem->attrs);
+ if (!node->base.vaddr) {
nvkm_error(subdev, "cannot allocate DMA memory\n");
return -ENOMEM;
}
@@ -611,18 +591,14 @@ gk20a_instmem_new(struct nvkm_device *device, int index,
imem->mm = &tdev->iommu.mm;
imem->domain = tdev->iommu.domain;
imem->iommu_pgshift = tdev->iommu.pgshift;
- imem->cpu_map = gk20a_instobj_cpu_map_iommu;
imem->iommu_bit = tdev->func->iommu_bit;

nvkm_info(&imem->base.subdev, "using IOMMU\n");
} else {
init_dma_attrs(&imem->attrs);
- /* We will access the memory through our own mapping */
dma_set_attr(DMA_ATTR_NON_CONSISTENT, &imem->attrs);
dma_set_attr(DMA_ATTR_WEAK_ORDERING, &imem->attrs);
dma_set_attr(DMA_ATTR_WRITE_COMBINE, &imem->attrs);
- dma_set_attr(DMA_ATTR_NO_KERNEL_MAPPING, &imem->attrs);
- imem->cpu_map = gk20a_instobj_cpu_map_dma;

nvkm_info(&imem->base.subdev, "using DMA API\n");
}
diff --git a/lib/include/nvif/os.h b/lib/include/nvif/os.h
index 2df30489179a..e8c06cb254dc 100644
--- a/lib/include/nvif/os.h
+++ b/lib/include/nvif/os.h
@@ -943,12 +943,6 @@ dma_unmap_page(struct device *pdev, dma_addr_t addr, int size, unsigned flags)
{
}

-static inline phys_addr_t
-dma_to_phys(struct device *dev, dma_addr_t addr)
-{
- return 0;
-}
-
/******************************************************************************
* PCI
*****************************************************************************/
--
2.6.2


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