[PATCH] media: s5p-mfc: Fix memdev DMA configuration

[PATCH] media: s5p-mfc: Fix memdev DMA configuration

[Robin Murphy]

Having of_reserved_mem_device_init() forcibly reconfigure DMA for all
callers, potentially overriding the work done by a bus-specific
.dma_configure method earlier, is at best a bad idea and at worst
actively harmful. If drivers really need virtual devices to own
dma-coherent memory, they should explicitly configure those devices
based on the appropriate firmware node as they create them.

It looks like the only driver not passing in a proper OF platform device
is s5p-mfc, so move the rogue of_dma_configure() call into that driver
where it logically belongs.

CC: Smitha T Murthy <smitha.t-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
CC: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
CC: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
---
 drivers/media/platform/s5p-mfc/s5p_mfc.c | 7 +++++++
 drivers/of/of_reserved_mem.c             | 4 ----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c
index 927a1235408d..77eb4a4511c1 100644
--- a/drivers/media/platform/s5p-mfc/s5p_mfc.c
+++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c
@@ -1094,6 +1094,13 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev,
 	child->dma_mask = dev->dma_mask;
 	child->release = s5p_mfc_memdev_release;
 
+	/*
+	 * The memdevs are not proper OF platform devices, so in order for them
+	 * to be treated as valid DMA masters we need a bit of a hack to force
+	 * them to inherit the MFC node's DMA configuration.
+	 */
+	of_dma_configure(child, dev->of_node, true);
+
 	if (device_add(child) == 0) {
 		ret = of_reserved_mem_device_init_by_idx(child, dev->of_node,
 							 idx);
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 895c83e0c7b6..4ef6f4485335 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -350,10 +350,6 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
 		mutex_lock(&of_rmem_assigned_device_mutex);
 		list_add(&rd->list, &of_rmem_assigned_device_list);
 		mutex_unlock(&of_rmem_assigned_device_mutex);
-		/* ensure that dma_ops is set for virtual devices
-		 * using reserved memory
-		 */
-		of_dma_configure(dev, np, true);
 
 		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
 	} else {
-- 
2.19.0.dirty

Re: [PATCH] media: s5p-mfc: Fix memdev DMA configuration

[Marek Szyprowski]

Hi Robin,

On 2018-09-12 18:45, Robin Murphy wrote:
> Having of_reserved_mem_device_init() forcibly reconfigure DMA for all
> callers, potentially overriding the work done by a bus-specific
> .dma_configure method earlier, is at best a bad idea and at worst
> actively harmful. If drivers really need virtual devices to own
> dma-coherent memory, they should explicitly configure those devices
> based on the appropriate firmware node as they create them.
>
> It looks like the only driver not passing in a proper OF platform device
> is s5p-mfc, so move the rogue of_dma_configure() call into that driver
> where it logically belongs.
>
> CC: Smitha T Murthy <smitha.t-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> CC: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> CC: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>

Right, after recent cleanup dma ops initialization, MFC driver is
a better place for calling of_dma_configure() on virtual devices.

Reviewed-by: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>

> ---
>   drivers/media/platform/s5p-mfc/s5p_mfc.c | 7 +++++++
>   drivers/of/of_reserved_mem.c             | 4 ----
>   2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c
> index 927a1235408d..77eb4a4511c1 100644
> --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c
> +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c
> @@ -1094,6 +1094,13 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev,
>   	child->dma_mask = dev->dma_mask;
>   	child->release = s5p_mfc_memdev_release;
>   
> +	/*
> +	 * The memdevs are not proper OF platform devices, so in order for them
> +	 * to be treated as valid DMA masters we need a bit of a hack to force
> +	 * them to inherit the MFC node's DMA configuration.
> +	 */
> +	of_dma_configure(child, dev->of_node, true);
> +
>   	if (device_add(child) == 0) {
>   		ret = of_reserved_mem_device_init_by_idx(child, dev->of_node,
>   							 idx);
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 895c83e0c7b6..4ef6f4485335 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -350,10 +350,6 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
>   		mutex_lock(&of_rmem_assigned_device_mutex);
>   		list_add(&rd->list, &of_rmem_assigned_device_list);
>   		mutex_unlock(&of_rmem_assigned_device_mutex);
> -		/* ensure that dma_ops is set for virtual devices
> -		 * using reserved memory
> -		 */
> -		of_dma_configure(dev, np, true);
>   
>   		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
>   	} else {

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [PATCH] media: s5p-mfc: Fix memdev DMA configuration

[Mauro Carvalho Chehab]

Em Fri, 14 Sep 2018 14:19:29 +0200
Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> escreveu:

> Hi Robin,
> 
> On 2018-09-12 18:45, Robin Murphy wrote:
> > Having of_reserved_mem_device_init() forcibly reconfigure DMA for all
> > callers, potentially overriding the work done by a bus-specific
> > .dma_configure method earlier, is at best a bad idea and at worst
> > actively harmful. If drivers really need virtual devices to own
> > dma-coherent memory, they should explicitly configure those devices
> > based on the appropriate firmware node as they create them.
> >
> > It looks like the only driver not passing in a proper OF platform device
> > is s5p-mfc, so move the rogue of_dma_configure() call into that driver
> > where it logically belongs.
> >
> > CC: Smitha T Murthy <smitha.t-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> > CC: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> > CC: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> > Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>  
> 
> Right, after recent cleanup dma ops initialization, MFC driver is
> a better place for calling of_dma_configure() on virtual devices.
> 
> Reviewed-by: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>

This patch seems to fit better via OF/DT tree. Not sure if it was
merged there yet. In any case:

Acked-by: Mauro Carvalho Chehab <mchehab+samsung-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

> 
> > ---
> >   drivers/media/platform/s5p-mfc/s5p_mfc.c | 7 +++++++
> >   drivers/of/of_reserved_mem.c             | 4 ----
> >   2 files changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c
> > index 927a1235408d..77eb4a4511c1 100644
> > --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c
> > +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c
> > @@ -1094,6 +1094,13 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev,
> >   	child->dma_mask = dev->dma_mask;
> >   	child->release = s5p_mfc_memdev_release;
> >   
> > +	/*
> > +	 * The memdevs are not proper OF platform devices, so in order for them
> > +	 * to be treated as valid DMA masters we need a bit of a hack to force
> > +	 * them to inherit the MFC node's DMA configuration.
> > +	 */
> > +	of_dma_configure(child, dev->of_node, true);
> > +
> >   	if (device_add(child) == 0) {
> >   		ret = of_reserved_mem_device_init_by_idx(child, dev->of_node,
> >   							 idx);
> > diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> > index 895c83e0c7b6..4ef6f4485335 100644
> > --- a/drivers/of/of_reserved_mem.c
> > +++ b/drivers/of/of_reserved_mem.c
> > @@ -350,10 +350,6 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
> >   		mutex_lock(&of_rmem_assigned_device_mutex);
> >   		list_add(&rd->list, &of_rmem_assigned_device_list);
> >   		mutex_unlock(&of_rmem_assigned_device_mutex);
> > -		/* ensure that dma_ops is set for virtual devices
> > -		 * using reserved memory
> > -		 */
> > -		of_dma_configure(dev, np, true);
> >   
> >   		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
> >   	} else {  
> 
> Best regards



Thanks,
Mauro