Subject: Re: [RFC PATCH V0 3/7] [media] dt-bindings: mt8183: Added DIP-SMEM dt-bindings

From: Frederic Chen <[email-masked]>
Date: Tue, 12 Feb 2019 17:50:00 +0800

Dear Laurent and Sakari,

On Sat, 2019-02-09 at 20:20 +0200, Laurent Pinchart wrote:
> Hello Frederic,
> 
> On Sat, Feb 09, 2019 at 05:59:35PM +0200, Sakari Ailus wrote:
> > Hi Frederic,
> > 
> > Thanks for the patchset.
> > 
> > Could you also cc the devicetree list, please?
> > 
> > On Fri, Feb 01, 2019 at 07:21:27PM +0800, Frederic Chen wrote:
> > > This patch adds the DT binding documentation for the shared memory
> > > between DIP (Digital Image Processing) unit of the camera ISP system
> > > and the co-processor in Mediatek SoCs.
> > > 
> > > Signed-off-by: Frederic Chen <[email-masked]>
> > > ---
> > >  .../bindings/media/mediatek,dip_smem.txt           | 29 ++++++++++++++++++++++
> > >  1 file changed, 29 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/media/mediatek,dip_smem.txt
> > > 
> > > diff --git a/Documentation/devicetree/bindings/media/mediatek,dip_smem.txt b/Documentation/devicetree/bindings/media/mediatek,dip_smem.txt
> > > new file mode 100644
> > > index 0000000..5533721
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/media/mediatek,dip_smem.txt
> > > @@ -0,0 +1,29 @@
> > > +Mediatek ISP Shared Memory Device
> > > +
> > > +Mediatek ISP Shared Memory Device is used to manage shared memory
> > > +among CPU, ISP IPs and coprocessor. It is associated with a reserved
> > > +memory region (Please see Documentation\devicetree\bindings\
> > > +reserved-memory\mediatek,reserve-memory-isp_smem.txt) and
> > 
> > s/\\/\//g;
> > 
> > > +and provide the context to allocate memory with dma addresses.
> 
> Does this represent a real device (as in IP core) in the SoC ? There
> seems to be no driver associated with the compatible string defined
> herein in this patch series, what is this node used for ?

It does not represent a real device. It is used for creating the
DIP-specific vb2 buffer allocation context (implemented
in /drivers/media/platform/mtk-isp/isp_50/dip/mtk_dip-smem-drv.c).
The compatible string has been renamed as “mediatek,dip_smem” in this
patch series and I will correct it in this binding document.

> 
> > > +Required properties:
> > > +- compatible: Should be "mediatek,isp_smem"
> > 
> > s/Should/Shall/
> > 
> > > +
> > > +- iommus: should point to the respective IOMMU block with master port
> > 
> > s/should/shall/
> > 
> > > +  as argument. Please set the ports which may be accessed
> > > +  through the common path. You can see
> > > +  Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
> > > +  for the detail.
> > > +
> > > +- mediatek,larb: must contain the local arbiters in the current Socs.
> > 
> > Perhaps "SoCs"?
> > 
> > > +  Please set the larb of camsys for Pass 1 and imgsys for DIP, or both
> > > +  if you are using all the camera function. You can see
> > > +  Documentation/devicetree/bindings/memory-controllers/
> > > +  mediatek,smi-larb.txt for the detail.
> > > +
> > > +Example:
> > > +	isp_smem: isp_smem {
> > > +		compatible = "mediatek,isp_smem";
> > > +		mediatek,larb = <&larb5>;
> > > +		iommus = <&iommu M4U_PORT_CAM_IMGI>;
> > > +	};
> 

Sincerely,

Frederic Chen

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