From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frederic Chen Subject: Re: [RFC PATCH V1 1/6] dt-bindings: mt8183: Add binding for DIP shared memory Date: Tue, 7 May 2019 22:22:05 +0800 Message-ID: <1557238925.11663.21.camel@mtksdccf07> References: <20190417104511.21514-1-frederic.chen@mediatek.com> <20190417104511.21514-2-frederic.chen@mediatek.com> <20190430011506.GA8514@bogus> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190430011506.GA8514@bogus> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Rob Herring Cc: shik@chromium.org, devicetree@vger.kernel.org, Sean.Cheng@mediatek.com, laurent.pinchart+renesas@ideasonboard.com, Rynn.Wu@mediatek.com, christie.yu@mediatek.com, srv_heupstream@mediatek.com, holmes.chiou@mediatek.com, suleiman@chromium.org, Jerry-ch.Chen@mediatek.com, tfiga@chromium.org, jungo.lin@mediatek.com, sj.huang@mediatek.com, yuzhao@chromium.org, hans.verkuil@cisco.com, zwisler@chromium.org, matthias.bgg@gmail.com, linux-mediatek@lists.infradead.org, mchehab@kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org List-Id: devicetree@vger.kernel.org Dear Rob, I appreciate your comments. On Mon, 2019-04-29 at 20:15 -0500, Rob Herring wrote: > On Wed, Apr 17, 2019 at 06:45:06PM +0800, Frederic Chen wrote: > > This patch adds the binding for describing the shared memory > > used to exchange configuration and tuning data between the > > co-processor and Digital Image Processing (DIP) unit of the > > camera ISP system on Mediatek SoCs. > > > > Signed-off-by: Frederic Chen > > --- > > .../mediatek,reserve-memory-dip_smem.txt | 45 +++++++++++++++++++ > > 1 file changed, 45 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt > > > > diff --git a/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt > > new file mode 100644 > > index 000000000000..64c001b476b9 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/reserved-memory/mediatek,reserve-memory-dip_smem.txt > > @@ -0,0 +1,45 @@ > > +Mediatek DIP Shared Memory binding > > + > > +This binding describes the shared memory, which serves the purpose of > > +describing the shared memory region used to exchange data between Digital > > +Image Processing (DIP) 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 Digital Image Processing (DIP) 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-dip_smem" > > Don't use '_'. I got it. I will use "mediatek,reserve-memory-dip-smem" instead in next version of the patch > > > + > > +- 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 > > Generally, you should pick either static or dynamic allocation for a > given binding. Static if there's some address restriction or sharing, > dynamic if not. > > Sounds like static in this case. > DIP reserved memory has address restriction so it is the static case. I would like to remove the dynamic allocation part and modify the description as following: - reg: required for DIP. The range must be between 0x00000400 and 0x100000000 due to the co-processor's addressing limitation. The size must be 26MB. Please see reserved-memory.txt for the detailed usage. > > + > > +- size: required for dynamic allocation. The unit is bytes. > > + If you want to enable the full feature of Digital Processing Unit, > > + you need 20 MB at least. > > + > > + > > +Example: > > + > > +The following example shows the DIP shared memory setup for MT8183. > > + > > + reserved-memory { > > + #address-cells = <2>; > > + #size-cells = <2>; > > + ranges; > > + reserve-memory-dip_smem { > > + compatible = "mediatek,reserve-memory-dip_smem"; > > + size = <0 0x1400000>; > > + alignment = <0 0x1000>; > > + alloc-ranges = <0 0x40000000 0 0x50000000>; > > + }; > > + }; > > -- > > 2.18.0 > > Sincerely, Frederic Chen