Re: [PATCH v5 6/8] drm/rockchip: Do not use DMA mapping API if attached to IOMMU domain

[Mark yao <mark.yao@rock-chips.com>]

On 2016年06月24日 10:13, Shunqian Zheng wrote:
> From: Tomasz Figa <tfiga@chromium.org>
>
> The API is not suitable for subsystems consisting of multiple devices
> and requires severe hacks to use it. To mitigate this, this patch
> implements allocation and address space management locally by using
> helpers provided by DRM framework, like other DRM drivers do, e.g.
> Tegra.
>
> This patch should not introduce any functional changes until the driver
> is made to attach subdevices into an IOMMU domain with the generic IOMMU
> API, which will happen in following patch. Based heavily on GEM
> implementation of Tegra DRM driver.

Acked-by: Mark Yao <mark.yao@rock-chips.com>
>
> Signed-off-by: Tomasz Figa <tfiga@chromium.org>
> Signed-off-by: Shunqian Zheng <zhengsq@rock-chips.com>
> ---
>   drivers/gpu/drm/rockchip/rockchip_drm_drv.h |   3 +
>   drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 221 ++++++++++++++++++++++++++--
>   drivers/gpu/drm/rockchip/rockchip_drm_gem.h |   9 ++
>   3 files changed, 222 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> index ea39329..5ab1223 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> @@ -30,6 +30,7 @@
>   
>   struct drm_device;
>   struct drm_connector;
> +struct iommu_domain;
>   
>   /*
>    * Rockchip drm private crtc funcs.
> @@ -61,6 +62,8 @@ struct rockchip_drm_private {
>   	struct drm_gem_object *fbdev_bo;
>   	const struct rockchip_crtc_funcs *crtc_funcs[ROCKCHIP_MAX_CRTC];
>   	struct drm_atomic_state *state;
> +	struct iommu_domain *domain;
> +	struct drm_mm mm;
>   };
>   
>   int rockchip_register_crtc_funcs(struct drm_crtc *crtc,
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
> index 394f92b..e7cd93d 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
> @@ -19,11 +19,135 @@
>   #include <drm/rockchip_drm.h>
>   
>   #include <linux/dma-attrs.h>
> +#include <linux/iommu.h>
>   
>   #include "rockchip_drm_drv.h"
>   #include "rockchip_drm_gem.h"
>   
> -static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj,
> +static int rockchip_gem_iommu_map(struct rockchip_gem_object *rk_obj)
> +{
> +	struct drm_device *drm = rk_obj->base.dev;
> +	struct rockchip_drm_private *private = drm->dev_private;
> +	int prot = IOMMU_READ | IOMMU_WRITE;
> +	ssize_t ret;
> +
> +	ret = drm_mm_insert_node_generic(&private->mm, &rk_obj->mm,
> +					 rk_obj->base.size, PAGE_SIZE,
> +					 0, 0, 0);
> +	if (ret < 0) {
> +		DRM_ERROR("out of I/O virtual memory: %zd\n", ret);
> +		return ret;
> +	}
> +
> +	rk_obj->dma_addr = rk_obj->mm.start;
> +
> +	ret = iommu_map_sg(private->domain, rk_obj->dma_addr, rk_obj->sgt->sgl,
> +			   rk_obj->sgt->nents, prot);
> +	if (ret < 0) {
> +		DRM_ERROR("failed to map buffer: %zd\n", ret);
> +		goto err_remove_node;
> +	}
> +
> +	rk_obj->size = ret;
> +
> +	return 0;
> +
> +err_remove_node:
> +	drm_mm_remove_node(&rk_obj->mm);
> +
> +	return ret;
> +}
> +
> +static int rockchip_gem_iommu_unmap(struct rockchip_gem_object *rk_obj)
> +{
> +	struct drm_device *drm = rk_obj->base.dev;
> +	struct rockchip_drm_private *private = drm->dev_private;
> +
> +	iommu_unmap(private->domain, rk_obj->dma_addr, rk_obj->size);
> +	drm_mm_remove_node(&rk_obj->mm);
> +
> +	return 0;
> +}
> +
> +static int rockchip_gem_get_pages(struct rockchip_gem_object *rk_obj)
> +{
> +	struct drm_device *drm = rk_obj->base.dev;
> +	int ret, i;
> +	struct scatterlist *s;
> +
> +	rk_obj->pages = drm_gem_get_pages(&rk_obj->base);
> +	if (IS_ERR(rk_obj->pages))
> +		return PTR_ERR(rk_obj->pages);
> +
> +	rk_obj->num_pages = rk_obj->base.size >> PAGE_SHIFT;
> +
> +	rk_obj->sgt = drm_prime_pages_to_sg(rk_obj->pages, rk_obj->num_pages);
> +	if (IS_ERR(rk_obj->sgt)) {
> +		ret = PTR_ERR(rk_obj->sgt);
> +		goto err_put_pages;
> +	}
> +
> +	/*
> +	 * Fake up the SG table so that dma_sync_sg_for_device() can be used
> +	 * to flush the pages associated with it.
> +	 *
> +	 * TODO: Replace this by drm_clflush_sg() once it can be implemented
> +	 * without relying on symbols that are not exported.
> +	 */
> +	for_each_sg(rk_obj->sgt->sgl, s, rk_obj->sgt->nents, i)
> +		sg_dma_address(s) = sg_phys(s);
> +
> +	dma_sync_sg_for_device(drm->dev, rk_obj->sgt->sgl, rk_obj->sgt->nents,
> +			       DMA_TO_DEVICE);
> +
> +	return 0;
> +
> +err_put_pages:
> +	drm_gem_put_pages(&rk_obj->base, rk_obj->pages, false, false);
> +	return ret;
> +}
> +
> +static void rockchip_gem_put_pages(struct rockchip_gem_object *rk_obj)
> +{
> +	sg_free_table(rk_obj->sgt);
> +	kfree(rk_obj->sgt);
> +	drm_gem_put_pages(&rk_obj->base, rk_obj->pages, false, false);
> +}
> +
> +static int rockchip_gem_alloc_iommu(struct rockchip_gem_object *rk_obj,
> +				    bool alloc_kmap)
> +{
> +	int ret;
> +
> +	ret = rockchip_gem_get_pages(rk_obj);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = rockchip_gem_iommu_map(rk_obj);
> +	if (ret < 0)
> +		goto err_free;
> +
> +	if (alloc_kmap) {
> +		rk_obj->kvaddr = vmap(rk_obj->pages, rk_obj->num_pages, VM_MAP,
> +				      pgprot_writecombine(PAGE_KERNEL));
> +		if (!rk_obj->kvaddr) {
> +			DRM_ERROR("failed to vmap() buffer\n");
> +			ret = -ENOMEM;
> +			goto err_unmap;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_unmap:
> +	rockchip_gem_iommu_unmap(rk_obj);
> +err_free:
> +	rockchip_gem_put_pages(rk_obj);
> +
> +	return ret;
> +}
> +
> +static int rockchip_gem_alloc_dma(struct rockchip_gem_object *rk_obj,
>   				  bool alloc_kmap)
>   {
>   	struct drm_gem_object *obj = &rk_obj->base;
> @@ -46,32 +170,93 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj,
>   	return 0;
>   }
>   
> -static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj)
> +static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj,
> +				  bool alloc_kmap)
>   {
>   	struct drm_gem_object *obj = &rk_obj->base;
>   	struct drm_device *drm = obj->dev;
> +	struct rockchip_drm_private *private = drm->dev_private;
>   
> -	dma_free_attrs(drm->dev, obj->size, rk_obj->kvaddr, rk_obj->dma_addr,
> -		       &rk_obj->dma_attrs);
> +	if (private->domain)
> +		return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap);
> +	else
> +		return rockchip_gem_alloc_dma(rk_obj, alloc_kmap);
>   }
>   
> -static int rockchip_drm_gem_object_mmap(struct drm_gem_object *obj,
> -					struct vm_area_struct *vma)
> +static void rockchip_gem_free_iommu(struct rockchip_gem_object *rk_obj)
> +{
> +	vunmap(rk_obj->kvaddr);
> +	rockchip_gem_iommu_unmap(rk_obj);
> +	rockchip_gem_put_pages(rk_obj);
> +}
>   
> +static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj)
>   {
> +	struct drm_gem_object *obj = &rk_obj->base;
> +	struct drm_device *drm = obj->dev;
> +
> +	dma_free_attrs(drm->dev, obj->size, rk_obj->kvaddr,
> +		       rk_obj->dma_addr, &rk_obj->dma_attrs);
> +}
> +
> +static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj)
> +{
> +	if (rk_obj->pages)
> +		rockchip_gem_free_iommu(rk_obj);
> +	else
> +		rockchip_gem_free_dma(rk_obj);
> +}
> +
> +static int rockchip_drm_gem_object_mmap_iommu(struct drm_gem_object *obj,
> +					      struct vm_area_struct *vma)
> +{
> +	struct rockchip_gem_object *rk_obj = to_rockchip_obj(obj);
> +	unsigned int i, count = obj->size >> PAGE_SHIFT;
> +	unsigned long user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> +	unsigned long uaddr = vma->vm_start;
>   	int ret;
> +
> +	if (user_count == 0 || user_count > count)
> +		return -ENXIO;
> +
> +	for (i = 0; i < user_count; i++) {
> +		ret = vm_insert_page(vma, uaddr, rk_obj->pages[i]);
> +		if (ret)
> +			return ret;
> +		uaddr += PAGE_SIZE;
> +	}
> +
> +	return 0;
> +}
> +
> +static int rockchip_drm_gem_object_mmap_dma(struct drm_gem_object *obj,
> +					    struct vm_area_struct *vma)
> +{
>   	struct rockchip_gem_object *rk_obj = to_rockchip_obj(obj);
>   	struct drm_device *drm = obj->dev;
>   
> +	return dma_mmap_attrs(drm->dev, vma, rk_obj->kvaddr, rk_obj->dma_addr,
> +			      obj->size, &rk_obj->dma_attrs);
> +}
> +
> +static int rockchip_drm_gem_object_mmap(struct drm_gem_object *obj,
> +					struct vm_area_struct *vma)
> +{
> +	int ret;
> +	struct rockchip_gem_object *rk_obj = to_rockchip_obj(obj);
> +
>   	/*
> -	 * dma_alloc_attrs() allocated a struct page table for rk_obj, so clear
> +	 * We allocated a struct page table for rk_obj, so clear
>   	 * VM_PFNMAP flag that was set by drm_gem_mmap_obj()/drm_gem_mmap().
>   	 */
>   	vma->vm_flags &= ~VM_PFNMAP;
>   	vma->vm_pgoff = 0;
>   
> -	ret = dma_mmap_attrs(drm->dev, vma, rk_obj->kvaddr, rk_obj->dma_addr,
> -			     obj->size, &rk_obj->dma_attrs);
> +	if (rk_obj->pages)
> +		ret = rockchip_drm_gem_object_mmap_iommu(obj, vma);
> +	else
> +		ret = rockchip_drm_gem_object_mmap_dma(obj, vma);
> +
>   	if (ret)
>   		drm_gem_vm_close(vma);
>   
> @@ -121,7 +306,7 @@ struct rockchip_gem_object *
>   
>   	obj = &rk_obj->base;
>   
> -	drm_gem_private_object_init(drm, obj, size);
> +	drm_gem_object_init(drm, obj, size);
>   
>   	ret = rockchip_gem_alloc_buf(rk_obj, alloc_kmap);
>   	if (ret)
> @@ -277,6 +462,9 @@ struct sg_table *rockchip_gem_prime_get_sg_table(struct drm_gem_object *obj)
>   	struct sg_table *sgt;
>   	int ret;
>   
> +	if (rk_obj->pages)
> +		return drm_prime_pages_to_sg(rk_obj->pages, rk_obj->num_pages);
> +
>   	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
>   	if (!sgt)
>   		return ERR_PTR(-ENOMEM);
> @@ -297,6 +485,10 @@ void *rockchip_gem_prime_vmap(struct drm_gem_object *obj)
>   {
>   	struct rockchip_gem_object *rk_obj = to_rockchip_obj(obj);
>   
> +	if (rk_obj->pages)
> +		return vmap(rk_obj->pages, rk_obj->num_pages, VM_MAP,
> +			    pgprot_writecombine(PAGE_KERNEL));
> +
>   	if (dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, &rk_obj->dma_attrs))
>   		return NULL;
>   
> @@ -305,5 +497,12 @@ void *rockchip_gem_prime_vmap(struct drm_gem_object *obj)
>   
>   void rockchip_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
>   {
> -	/* Nothing to do */
> +	struct rockchip_gem_object *rk_obj = to_rockchip_obj(obj);
> +
> +	if (rk_obj->pages) {
> +		vunmap(vaddr);
> +		return;
> +	}
> +
> +	/* Nothing to do if allocated by DMA mapping API. */
>   }
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.h b/drivers/gpu/drm/rockchip/rockchip_drm_gem.h
> index 3584b94..6aa61b2 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.h
> @@ -23,7 +23,16 @@ struct rockchip_gem_object {
>   
>   	void *kvaddr;
>   	dma_addr_t dma_addr;
> +
> +	/* Used when IOMMU is disabled */
>   	struct dma_attrs dma_attrs;
> +
> +	/* Used when IOMMU is enabled */
> +	struct drm_mm_node mm;
> +	unsigned long num_pages;
> +	struct page **pages;
> +	struct sg_table *sgt;
> +	size_t size;
>   };
>   
>   struct sg_table *rockchip_gem_prime_get_sg_table(struct drm_gem_object *obj);


-- 
Ｍark Yao


_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel