diff mbox series

[RFC,V1,1/6] dt-bindings: mt8183: Add binding for FD shared memory

Message ID 20190423104505.38778-2-Jerry-Ch.chen@mediatek.com (mailing list archive)
State RFC
Headers show
Series media: platform: Add support for Face Detection (FD) on mt8183 SoC | expand

Commit Message

Jerry-ch Chen April 23, 2019, 10:45 a.m. UTC 
From: Jerry-ch Chen <jerry-ch.chen@mediatek.com>

This patch adds the binding for describing the shared memory
used to exchange meta data between the co-processor and Face
Detection (FD) unit of the camera system on Mediatek SoCs.

Signed-off-by: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
---
 .../mediatek,reserve-memory-fd_smem.txt       | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt

Comments

Rob Herring (Arm) May 1, 2019, 10:45 p.m. UTC | #1 
On Tue, Apr 23, 2019 at 06:45:00PM +0800, Jerry-ch Chen wrote:
> From: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
> 
> This patch adds the binding for describing the shared memory
> used to exchange meta data between the co-processor and Face
> Detection (FD) unit of the camera system on Mediatek SoCs.
> 
> Signed-off-by: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
> ---
>  .../mediatek,reserve-memory-fd_smem.txt       | 44 +++++++++++++++++++
>  1 file changed, 44 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
> 
> diff --git a/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
> new file mode 100644
> index 000000000000..52ae5071e238
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
> @@ -0,0 +1,44 @@
> +Mediatek FD Shared Memory binding
> +
> +This binding describes the shared memory, which serves the purpose of
> +describing the shared memory region used to exchange data between Face
> +Detection hardware (FD) and co-processor in Mediatek SoCs.
> +
> +The co-processor doesn't have the iommu so we need to use the physical
> +address to access the shared buffer in the firmware.
> +
> +The Face Detection hardware (FD) can access memory through mt8183 IOMMU so
> +it can use dma address to access the memory region.
> +(See iommu/mediatek,iommu.txt for the detailed description of Mediatek IOMMU)
> +
> +
> +Required properties:
> +
> +- compatible: must be "mediatek,reserve-memory-fd_smem"
> +
> +- reg: required for static allocation (see reserved-memory.txt for
> +  the detailed usage)
> +
> +- alloc-range: required for dynamic allocation. The range must
> +  between 0x00000400 and 0x100000000 due to the co-processer's
> +  addressing limitation
> +
> +- size: required for dynamic allocation. The unit is bytes.
> +  for Face Detection Unit, you need 1 MB at least.

What's the most?

I don't think you really need reserved memory here if you don't need a 
fixed address. The size is not that big that a contiguous allocation 
shouldn't be a problem (though with IOMMU you don't even need that). 
'dma-ranges' can be used to set the kernel's dma mask and ensure a 
range below 0x10000000.

Rob
Jerry-ch Chen May 20, 2019, 10:04 a.m. UTC | #2 
Hi Rob,

Thank you for your comments.

On Thu, 2019-05-02 at 06:45 +0800, Rob Herring wrote:
> On Tue, Apr 23, 2019 at 06:45:00PM +0800, Jerry-ch Chen wrote:
> > From: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
> > 
> > This patch adds the binding for describing the shared memory
> > used to exchange meta data between the co-processor and Face
> > Detection (FD) unit of the camera system on Mediatek SoCs.
> > 
> > Signed-off-by: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
> > ---
> >  .../mediatek,reserve-memory-fd_smem.txt       | 44 +++++++++++++++++++
> >  1 file changed, 44 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
> > new file mode 100644
> > index 000000000000..52ae5071e238
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
> > @@ -0,0 +1,44 @@
> > +Mediatek FD Shared Memory binding
> > +
> > +This binding describes the shared memory, which serves the purpose of
> > +describing the shared memory region used to exchange data between Face
> > +Detection hardware (FD) and co-processor in Mediatek SoCs.
> > +
> > +The co-processor doesn't have the iommu so we need to use the physical
> > +address to access the shared buffer in the firmware.
> > +
> > +The Face Detection hardware (FD) can access memory through mt8183 IOMMU so
> > +it can use dma address to access the memory region.
> > +(See iommu/mediatek,iommu.txt for the detailed description of Mediatek IOMMU)
> > +
> > +
> > +Required properties:
> > +
> > +- compatible: must be "mediatek,reserve-memory-fd_smem"
> > +
> > +- reg: required for static allocation (see reserved-memory.txt for
> > +  the detailed usage)
> > +
> > +- alloc-range: required for dynamic allocation. The range must
> > +  between 0x00000400 and 0x100000000 due to the co-processer's
> > +  addressing limitation
> > +
> > +- size: required for dynamic allocation. The unit is bytes.
> > +  for Face Detection Unit, you need 1 MB at least.
> 
> What's the most?
> 

For this part, we would like to revise as following:

alloc-range: required for dynamic allocation. The range must between
0x40000000 and 0x100000000 due to the co-processor's addressing
limitation

size: required for dynamic allocation. The unit is bytes.
for Face Detection Unit, you need 518KB.

> I don't think you really need reserved memory here if you don't need a 
> fixed address. The size is not that big that a contiguous allocation 
> shouldn't be a problem (though with IOMMU you don't even need that). 
> 'dma-ranges' can be used to set the kernel's dma mask and ensure a 
> range below 0x10000000.
> 

FD driver might be able to use the FD memory pool inside the scp
reserved memory instead of declaring reserved memory here.
would you have any suggestion if so?

Sincerely,
	Jerry


> Rob
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
new file mode 100644
index 000000000000..52ae5071e238
--- /dev/null
+++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-fd_smem.txt
@@ -0,0 +1,44 @@ 
+Mediatek FD Shared Memory binding
+
+This binding describes the shared memory, which serves the purpose of
+describing the shared memory region used to exchange data between Face
+Detection hardware (FD) and co-processor in Mediatek SoCs.
+
+The co-processor doesn't have the iommu so we need to use the physical
+address to access the shared buffer in the firmware.
+
+The Face Detection hardware (FD) can access memory through mt8183 IOMMU so
+it can use dma address to access the memory region.
+(See iommu/mediatek,iommu.txt for the detailed description of Mediatek IOMMU)
+
+
+Required properties:
+
+- compatible: must be "mediatek,reserve-memory-fd_smem"
+
+- reg: required for static allocation (see reserved-memory.txt for
+  the detailed usage)
+
+- alloc-range: required for dynamic allocation. The range must
+  between 0x00000400 and 0x100000000 due to the co-processer's
+  addressing limitation
+
+- size: required for dynamic allocation. The unit is bytes.
+  for Face Detection Unit, you need 1 MB at least.
+
+
+Example:
+
+The following example shows the FD shared memory setup for MT8183.
+
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+		reserve-memory-fd_smem {
+			compatible = "mediatek,reserve-memory-fd_smem";
+			size = <0 0x00100000>;
+			alignment = <0 0x1000>;
+			alloc-ranges = <0 0x40000000 0 0x100000000>;
+		};
+	};
\ No newline at end of file