Re: [PATCH] cleanup: Add 'struct dev' in the TTM layer to be passed in for DMA API calls.

Thomas Hellstrom
2011-03-08T20:52:54Z

Hi, Konrad,

Is passing a struct device to the DMA api really *strictly* necessary?

I'd like to avoid that at all cost, since we don't want pages that are
backing buffer objects
(coherent pages) to be associated with a specific device.

The reason for this is that we probably soon will want to move ttm
buffer objects between devices, and that should ideally be a simple
operation: If the memory type the buffer object currently resides in is
not shared between two devices, then move it out to system memory and
change its struct bo_device pointer.

If pages are associated with a specific device, this will become much
harder. Basically we need to change backing pages and copy all the data.

/Thomas

On 03/08/2011 04:39 PM, Konrad Rzeszutek Wilk wrote:
> These two patches are not strictly required but they do a bit of
> cleanup and also fix a false reporting issue when the kernel is compiled
> with CONFIG_DEBUG_DMA_API.
>
> Essentially the patchset modifies 'struct ttm_tt' and 'struct ttm_bo_device'
> to contain a pointer to 'struct device'. Passing of the 'struct device'
> is done via the 'tt_bo_device_init'. The 'struct device' is then used
> during the allocation/deallocation of pages when TTM_PAGE_FLAG_DMA32 flag
> is set.
>
> At first it seems that we would need to keep a copy of
> 'struct device' in the struct ttm_bo_device only and use that. However,
> when 'ttm_tt_destroy' is called it sets ttm->be (which contains
> the 'struct ttm_bo_device') to NULL so we cannot use it. Hence
> we copy the 'struct device' pointer to the 'struct ttm_tm' and keep
> it there.
>
> I've put the patches on:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git devel/ttm.pci-api.v5
>
> The testing was a bit difficult b/c I could not persuade the machine to unload
> either the nouveau or radeon driver (I had a serial console hooked so I figured
> it would fallback to that?). Ended up calling 'unbind' on the
> /sys/pci/.../$BDF/driver/[radeon,nouveau] to trigger the de-allocation path.
>
> Thomas,
>
> What is the best way to test vmw-gfx*? Does the Workstation (5?) support
> this particular frontend?
>
> Konrad Rzeszutek Wilk (2):
> ttm: Include the 'struct dev' when using the DMA API.
> ttm: Pass in 'struct device' to TTM so it can do DMA API on behalf of device.
>
> drivers/gpu/drm/nouveau/nouveau_mem.c | 3 ++-
> drivers/gpu/drm/radeon/radeon_ttm.c | 3 ++-
> drivers/gpu/drm/ttm/ttm_bo.c | 4 +++-
> drivers/gpu/drm/ttm/ttm_page_alloc.c | 11 ++++++-----
> drivers/gpu/drm/ttm/ttm_tt.c | 5 +++--
> drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 4 ++--
> include/drm/ttm/ttm_bo_driver.h | 7 ++++++-
> include/drm/ttm/ttm_page_alloc.h | 8 ++++++--
> 8 files changed, 30 insertions(+), 15 deletions(-)
>
>
> The full diff:
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_mem.c b/drivers/gpu/drm/nouveau/nouveau_mem.c
> index 26347b7..3706156 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_mem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_mem.c
> @@ -412,7 +412,8 @@ nouveau_mem_vram_init(struct drm_device *dev)
> ret = ttm_bo_device_init(&dev_priv->ttm.bdev,
> dev_priv->ttm.bo_global_ref.ref.object,
> &nouveau_bo_driver, DRM_FILE_PAGE_OFFSET,
> - dma_bits<= 32 ? true : false);
> + dma_bits<= 32 ? true : false,
> + dev->dev);
> if (ret) {
> NV_ERROR(dev, "Error initialising bo driver: %d\n", ret);
> return ret;
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
> index 9ead11f..371890c 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -517,7 +517,8 @@ int radeon_ttm_init(struct radeon_device *rdev)
> r = ttm_bo_device_init(&rdev->mman.bdev,
> rdev->mman.bo_global_ref.ref.object,
> &radeon_bo_driver, DRM_FILE_PAGE_OFFSET,
> - rdev->need_dma32);
> + rdev->need_dma32,
> + rdev->dev);
> if (r) {
> DRM_ERROR("failed initializing buffer object driver(%d).\n", r);
> return r;
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index af61fc2..278a2d3 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -1526,12 +1526,14 @@ int ttm_bo_device_init(struct ttm_bo_device *bdev,
> struct ttm_bo_global *glob,
> struct ttm_bo_driver *driver,
> uint64_t file_page_offset,
> - bool need_dma32)
> + bool need_dma32,
> + struct device *dev)
> {
> int ret = -EINVAL;
>
> rwlock_init(&bdev->vm_lock);
> bdev->driver = driver;
> + bdev->dev = dev;
>
> memset(bdev->man, 0, sizeof(bdev->man));
>
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index 737a2a2..35849db 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> @@ -664,7 +664,7 @@ out:
> */
> int ttm_get_pages(struct list_head *pages, int flags,
> enum ttm_caching_state cstate, unsigned count,
> - dma_addr_t *dma_address)
> + dma_addr_t *dma_address, struct device *dev)
> {
> struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
> struct page *p = NULL;
> @@ -685,7 +685,7 @@ int ttm_get_pages(struct list_head *pages, int flags,
> for (r = 0; r< count; ++r) {
> if ((flags& TTM_PAGE_FLAG_DMA32)&& dma_address) {
> void *addr;
> - addr = dma_alloc_coherent(NULL, PAGE_SIZE,
> + addr = dma_alloc_coherent(dev, PAGE_SIZE,
> &dma_address[r],
> gfp_flags);
> if (addr == NULL)
> @@ -730,7 +730,7 @@ int ttm_get_pages(struct list_head *pages, int flags,
> printk(KERN_ERR TTM_PFX
> "Failed to allocate extra pages "
> "for large request.");
> - ttm_put_pages(pages, 0, flags, cstate, NULL);
> + ttm_put_pages(pages, 0, flags, cstate, NULL, NULL);
> return r;
> }
> }
> @@ -741,7 +741,8 @@ int ttm_get_pages(struct list_head *pages, int flags,
>
> /* Put all pages in pages list to correct pool to wait for reuse */
> void ttm_put_pages(struct list_head *pages, unsigned page_count, int flags,
> - enum ttm_caching_state cstate, dma_addr_t *dma_address)
> + enum ttm_caching_state cstate, dma_addr_t *dma_address,
> + struct device *dev)
> {
> unsigned long irq_flags;
> struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
> @@ -757,7 +758,7 @@ void ttm_put_pages(struct list_head *pages, unsigned page_count, int flags,
> void *addr = page_address(p);
> WARN_ON(!addr || !dma_address[r]);
> if (addr)
> - dma_free_coherent(NULL, PAGE_SIZE,
> + dma_free_coherent(dev, PAGE_SIZE,
> addr,
> dma_address[r]);
> dma_address[r] = 0;
> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
> index 86d5b17..354f9d9 100644
> --- a/drivers/gpu/drm/ttm/ttm_tt.c
> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
> @@ -110,7 +110,7 @@ static struct page *__ttm_tt_get_page(struct ttm_tt *ttm, int index)
> INIT_LIST_HEAD(&h);
>
> ret = ttm_get_pages(&h, ttm->page_flags, ttm->caching_state, 1,
> - &ttm->dma_address[index]);
> + &ttm->dma_address[index], ttm->dev);
>
> if (ret != 0)
> return NULL;
> @@ -304,7 +304,7 @@ static void ttm_tt_free_alloced_pages(struct ttm_tt *ttm)
> }
> }
> ttm_put_pages(&h, count, ttm->page_flags, ttm->caching_state,
> - ttm->dma_address);
> + ttm->dma_address, ttm->dev);
> ttm->state = tt_unpopulated;
> ttm->first_himem_page = ttm->num_pages;
> ttm->last_lomem_page = -1;
> @@ -397,6 +397,7 @@ struct ttm_tt *ttm_tt_create(struct ttm_bo_device *bdev, unsigned long size,
> ttm->last_lomem_page = -1;
> ttm->caching_state = tt_cached;
> ttm->page_flags = page_flags;
> + ttm->dev = bdev->dev;
>
> ttm->dummy_read_page = dummy_read_page;
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> index 10ca97e..803d979 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> @@ -322,11 +322,11 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
> ttm_lock_set_kill(&dev_priv->fbdev_master.lock, false, SIGTERM);
> dev_priv->active_master =&dev_priv->fbdev_master;
>
> -
> ret = ttm_bo_device_init(&dev_priv->bdev,
> dev_priv->bo_global_ref.ref.object,
> &vmw_bo_driver, VMWGFX_FILE_PAGE_OFFSET,
> - false);
> + false,
> + dev->dev);
> if (unlikely(ret != 0)) {
> DRM_ERROR("Failed initializing TTM buffer object driver.\n");
> goto out_err1;
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index efed082..2024a74 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -177,6 +177,7 @@ struct ttm_tt {
> tt_unpopulated,
> } state;
> dma_addr_t *dma_address;
> + struct device *dev;
> };
>
> #define TTM_MEMTYPE_FLAG_FIXED (1<< 0) /* Fixed (on-card) PCI memory */
> @@ -551,6 +552,7 @@ struct ttm_bo_device {
> struct list_head device_list;
> struct ttm_bo_global *glob;
> struct ttm_bo_driver *driver;
> + struct device *dev;
> rwlock_t vm_lock;
> struct ttm_mem_type_manager man[TTM_NUM_MEM_TYPES];
> spinlock_t fence_lock;
> @@ -791,6 +793,8 @@ extern int ttm_bo_device_release(struct ttm_bo_device *bdev);
> * @file_page_offset: Offset into the device address space that is available
> * for buffer data. This ensures compatibility with other users of the
> * address space.
> + * @need_dma32: Allocate pages under 4GB
> + * @dev: 'struct device' of the PCI device.
> *
> * Initializes a struct ttm_bo_device:
> * Returns:
> @@ -799,7 +803,8 @@ extern int ttm_bo_device_release(struct ttm_bo_device *bdev);
> extern int ttm_bo_device_init(struct ttm_bo_device *bdev,
> struct ttm_bo_global *glob,
> struct ttm_bo_driver *driver,
> - uint64_t file_page_offset, bool need_dma32);
> + uint64_t file_page_offset, bool need_dma32,
> + struct device *dev);
>
> /**
> * ttm_bo_unmap_virtual
> diff --git a/include/drm/ttm/ttm_page_alloc.h b/include/drm/ttm/ttm_page_alloc.h
> index 8062890..ccb6b7a 100644
> --- a/include/drm/ttm/ttm_page_alloc.h
> +++ b/include/drm/ttm/ttm_page_alloc.h
> @@ -37,12 +37,14 @@
> * @cstate: ttm caching state for the page.
> * @count: number of pages to allocate.
> * @dma_address: The DMA (bus) address of pages (if TTM_PAGE_FLAG_DMA32 set).
> + * @dev: struct device for appropiate DMA accounting.
> */
> int ttm_get_pages(struct list_head *pages,
> int flags,
> enum ttm_caching_state cstate,
> unsigned count,
> - dma_addr_t *dma_address);
> + dma_addr_t *dma_address,
> + struct device *dev);
> /**
> * Put linked list of pages to pool.
> *
> @@ -52,12 +54,14 @@ int ttm_get_pages(struct list_head *pages,
> * @flags: ttm flags for page allocation.
> * @cstate: ttm caching state.
> * @dma_address: The DMA (bus) address of pages (if TTM_PAGE_FLAG_DMA32 set).
> + * @dev: struct device for appropiate DMA accounting.
> */
> void ttm_put_pages(struct list_head *pages,
> unsigned page_count,
> int flags,
> enum ttm_caching_state cstate,
> - dma_addr_t *dma_address);
> + dma_addr_t *dma_address,
> + struct device *dev);
> /**
> * Initialize pool allocator.
> */
>