[PATCH v7 07/36] drm: exynos: use common helper for a scatterlist contiguity check

[PATCH v7 07/36] drm: exynos: use common helper for a scatterlist contiguity check

[Marek Szyprowski]

Use common helper for checking the contiguity of the imported dma-buf.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c | 23 +++--------------------
 1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index efa476858db5..1716a023bca0 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -431,27 +431,10 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device *dev,
 {
 	struct exynos_drm_gem *exynos_gem;
 
-	if (sgt->nents < 1)
+	/* check if the entries in the sg_table are contiguous */
+	if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size) {
+		DRM_ERROR("buffer chunks must be mapped contiguously");
 		return ERR_PTR(-EINVAL);
-
-	/*
-	 * Check if the provided buffer has been mapped as contiguous
-	 * into DMA address space.
-	 */
-	if (sgt->nents > 1) {
-		dma_addr_t next_addr = sg_dma_address(sgt->sgl);
-		struct scatterlist *s;
-		unsigned int i;
-
-		for_each_sg(sgt->sgl, s, sgt->nents, i) {
-			if (!sg_dma_len(s))
-				break;
-			if (sg_dma_address(s) != next_addr) {
-				DRM_ERROR("buffer chunks must be mapped contiguously");
-				return ERR_PTR(-EINVAL);
-			}
-			next_addr = sg_dma_address(s) + sg_dma_len(s);
-		}
 	}
 
 	exynos_gem = exynos_drm_gem_init(dev, attach->dmabuf->size);
-- 
2.17.1

[PATCH v7 08/36] drm: exynos: fix common struct sg_table related issues

[Marek Szyprowski]

The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().

struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.

To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_g2d.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index fcee33a43aca..7014a8cd971a 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -395,8 +395,8 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
 		return;
 
 out:
-	dma_unmap_sg(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt->sgl,
-			g2d_userptr->sgt->nents, DMA_BIDIRECTIONAL);
+	dma_unmap_sgtable(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt,
+			  DMA_BIDIRECTIONAL, 0);
 
 	pages = frame_vector_pages(g2d_userptr->vec);
 	if (!IS_ERR(pages)) {
@@ -511,10 +511,10 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
 
 	g2d_userptr->sgt = sgt;
 
-	if (!dma_map_sg(to_dma_dev(g2d->drm_dev), sgt->sgl, sgt->nents,
-				DMA_BIDIRECTIONAL)) {
+	ret = dma_map_sgtable(to_dma_dev(g2d->drm_dev), sgt,
+			      DMA_BIDIRECTIONAL, 0);
+	if (ret) {
 		DRM_DEV_ERROR(g2d->dev, "failed to map sgt with dma region.\n");
-		ret = -ENOMEM;
 		goto err_sg_free_table;
 	}
 
-- 
2.17.1

Re: [PATCH v7 07/36] drm: exynos: use common helper for a scatterlist contiguity check

[Andrzej Hajda]

Hi,

On 19.06.2020 12:36, Marek Szyprowski wrote:
> Use common helper for checking the contiguity of the imported dma-buf.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>   drivers/gpu/drm/exynos/exynos_drm_gem.c | 23 +++--------------------
>   1 file changed, 3 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> index efa476858db5..1716a023bca0 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> @@ -431,27 +431,10 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device *dev,
>   {
>   	struct exynos_drm_gem *exynos_gem;
>   
> -	if (sgt->nents < 1)
> +	/* check if the entries in the sg_table are contiguous */
> +	if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size) {
> +		DRM_ERROR("buffer chunks must be mapped contiguously");
>   		return ERR_PTR(-EINVAL);
> -
> -	/*
> -	 * Check if the provided buffer has been mapped as contiguous
> -	 * into DMA address space.
> -	 */
> -	if (sgt->nents > 1) {
> -		dma_addr_t next_addr = sg_dma_address(sgt->sgl);
> -		struct scatterlist *s;
> -		unsigned int i;
> -
> -		for_each_sg(sgt->sgl, s, sgt->nents, i) {
> -			if (!sg_dma_len(s))
> -				break;
> -			if (sg_dma_address(s) != next_addr) {
> -				DRM_ERROR("buffer chunks must be mapped contiguously");
> -				return ERR_PTR(-EINVAL);
> -			}
> -			next_addr = sg_dma_address(s) + sg_dma_len(s);
> -		}
>   	}


Reviewed-by <a.hajda@samsung.com>


Regards
Andrzej
>   
>   	exynos_gem = exynos_drm_gem_init(dev, attach->dmabuf->size);

Re: [PATCH v7 08/36] drm: exynos: fix common struct sg_table related issues

[Andrzej Hajda]

On 19.06.2020 12:36, Marek Szyprowski wrote:
> The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
> returns the number of the created entries in the DMA address space.
> However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
> dma_unmap_sg must be called with the original number of the entries
> passed to the dma_map_sg().
>
> struct sg_table is a common structure used for describing a non-contiguous
> memory buffer, used commonly in the DRM and graphics subsystems. It
> consists of a scatterlist with memory pages and DMA addresses (sgl entry),
> as well as the number of scatterlist entries: CPU pages (orig_nents entry)
> and DMA mapped pages (nents entry).
>
> It turned out that it was a common mistake to misuse nents and orig_nents
> entries, calling DMA-mapping functions with a wrong number of entries or
> ignoring the number of mapped entries returned by the dma_map_sg()
> function.
>
> To avoid such issues, lets use a common dma-mapping wrappers operating
> directly on the struct sg_table objects and use scatterlist page
> iterators where possible. This, almost always, hides references to the
> nents and orig_nents entries, making the code robust, easier to follow
> and copy/paste safe.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Reviewed-by <a.hajda@samsung.com>

Regards
Andrzej


> ---
>   drivers/gpu/drm/exynos/exynos_drm_g2d.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> index fcee33a43aca..7014a8cd971a 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> @@ -395,8 +395,8 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
>   		return;
>   
>   out:
> -	dma_unmap_sg(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt->sgl,
> -			g2d_userptr->sgt->nents, DMA_BIDIRECTIONAL);
> +	dma_unmap_sgtable(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt,
> +			  DMA_BIDIRECTIONAL, 0);
>   
>   	pages = frame_vector_pages(g2d_userptr->vec);
>   	if (!IS_ERR(pages)) {
> @@ -511,10 +511,10 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
>   
>   	g2d_userptr->sgt = sgt;
>   
> -	if (!dma_map_sg(to_dma_dev(g2d->drm_dev), sgt->sgl, sgt->nents,
> -				DMA_BIDIRECTIONAL)) {
> +	ret = dma_map_sgtable(to_dma_dev(g2d->drm_dev), sgt,
> +			      DMA_BIDIRECTIONAL, 0);
> +	if (ret) {
>   		DRM_DEV_ERROR(g2d->dev, "failed to map sgt with dma region.\n");
> -		ret = -ENOMEM;
>   		goto err_sg_free_table;
>   	}
>   

Re: [PATCH v7 07/36] drm: exynos: use common helper for a scatterlist contiguity check

[Andrzej Hajda]

On 07.07.2020 11:35, Andrzej Hajda wrote:
> Hi,
>
> On 19.06.2020 12:36, Marek Szyprowski wrote:
>> Use common helper for checking the contiguity of the imported dma-buf.
>>
>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Just fixing my signature :)

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

Regards
Andrzej

Re: [PATCH v7 08/36] drm: exynos: fix common struct sg_table related issues

[Andrzej Hajda]

On 07.07.2020 11:40, Andrzej Hajda wrote:
> On 19.06.2020 12:36, Marek Szyprowski wrote:
>> The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
>> returns the number of the created entries in the DMA address space.
>> However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
>> dma_unmap_sg must be called with the original number of the entries
>> passed to the dma_map_sg().
>>
>> struct sg_table is a common structure used for describing a non-contiguous
>> memory buffer, used commonly in the DRM and graphics subsystems. It
>> consists of a scatterlist with memory pages and DMA addresses (sgl entry),
>> as well as the number of scatterlist entries: CPU pages (orig_nents entry)
>> and DMA mapped pages (nents entry).
>>
>> It turned out that it was a common mistake to misuse nents and orig_nents
>> entries, calling DMA-mapping functions with a wrong number of entries or
>> ignoring the number of mapped entries returned by the dma_map_sg()
>> function.
>>
>> To avoid such issues, lets use a common dma-mapping wrappers operating
>> directly on the struct sg_table objects and use scatterlist page
>> iterators where possible. This, almost always, hides references to the
>> nents and orig_nents entries, making the code robust, easier to follow
>> and copy/paste safe.
>>
>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
>

Just fixing my signature :)

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

Regards
Andrzej

Re: [PATCH v7 08/36] drm: exynos: fix common struct sg_table related issues

[Inki Dae]

20. 6. 19. 오후 7:36에 Marek Szyprowski 이(가) 쓴 글:
> The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
> returns the number of the created entries in the DMA address space.
> However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
> dma_unmap_sg must be called with the original number of the entries
> passed to the dma_map_sg().
> 
> struct sg_table is a common structure used for describing a non-contiguous
> memory buffer, used commonly in the DRM and graphics subsystems. It
> consists of a scatterlist with memory pages and DMA addresses (sgl entry),
> as well as the number of scatterlist entries: CPU pages (orig_nents entry)
> and DMA mapped pages (nents entry).
> 
> It turned out that it was a common mistake to misuse nents and orig_nents
> entries, calling DMA-mapping functions with a wrong number of entries or
> ignoring the number of mapped entries returned by the dma_map_sg()
> function.
> 
> To avoid such issues, lets use a common dma-mapping wrappers operating
> directly on the struct sg_table objects and use scatterlist page
> iterators where possible. This, almost always, hides references to the
> nents and orig_nents entries, making the code robust, easier to follow
> and copy/paste safe.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Acked-by : Inki Dae <inki.dae@samsung.com>

Thanks,
Inki Dae

> ---
>  drivers/gpu/drm/exynos/exynos_drm_g2d.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> index fcee33a43aca..7014a8cd971a 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> @@ -395,8 +395,8 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
>  		return;
>  
>  out:
> -	dma_unmap_sg(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt->sgl,
> -			g2d_userptr->sgt->nents, DMA_BIDIRECTIONAL);
> +	dma_unmap_sgtable(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt,
> +			  DMA_BIDIRECTIONAL, 0);
>  
>  	pages = frame_vector_pages(g2d_userptr->vec);
>  	if (!IS_ERR(pages)) {
> @@ -511,10 +511,10 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
>  
>  	g2d_userptr->sgt = sgt;
>  
> -	if (!dma_map_sg(to_dma_dev(g2d->drm_dev), sgt->sgl, sgt->nents,
> -				DMA_BIDIRECTIONAL)) {
> +	ret = dma_map_sgtable(to_dma_dev(g2d->drm_dev), sgt,
> +			      DMA_BIDIRECTIONAL, 0);
> +	if (ret) {
>  		DRM_DEV_ERROR(g2d->dev, "failed to map sgt with dma region.\n");
> -		ret = -ENOMEM;
>  		goto err_sg_free_table;
>  	}
>  
> 

Re: [PATCH v7 07/36] drm: exynos: use common helper for a scatterlist contiguity check

[Inki Dae]

20. 6. 19. 오후 7:36에 Marek Szyprowski 이(가) 쓴 글:
> Use common helper for checking the contiguity of the imported dma-buf.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Acked-by : Inki Dae <inki.dae@samsung.com>

Thanks,
Inki Dae

> ---
>  drivers/gpu/drm/exynos/exynos_drm_gem.c | 23 +++--------------------
>  1 file changed, 3 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> index efa476858db5..1716a023bca0 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> @@ -431,27 +431,10 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device *dev,
>  {
>  	struct exynos_drm_gem *exynos_gem;
>  
> -	if (sgt->nents < 1)
> +	/* check if the entries in the sg_table are contiguous */
> +	if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size) {
> +		DRM_ERROR("buffer chunks must be mapped contiguously");
>  		return ERR_PTR(-EINVAL);
> -
> -	/*
> -	 * Check if the provided buffer has been mapped as contiguous
> -	 * into DMA address space.
> -	 */
> -	if (sgt->nents > 1) {
> -		dma_addr_t next_addr = sg_dma_address(sgt->sgl);
> -		struct scatterlist *s;
> -		unsigned int i;
> -
> -		for_each_sg(sgt->sgl, s, sgt->nents, i) {
> -			if (!sg_dma_len(s))
> -				break;
> -			if (sg_dma_address(s) != next_addr) {
> -				DRM_ERROR("buffer chunks must be mapped contiguously");
> -				return ERR_PTR(-EINVAL);
> -			}
> -			next_addr = sg_dma_address(s) + sg_dma_len(s);
> -		}
>  	}
>  
>  	exynos_gem = exynos_drm_gem_init(dev, attach->dmabuf->size);
>