Re: [PATCH v4 3/5] dt/bindings: qcom_nandc: Add DT bindings

[Archit Taneja]

Hi Boris,

On 12/16/2015 12:03 PM, Boris Brezillon wrote:
> Hi Archit,
>
> Sorry for the late review, but there are a few things I think should be
> addressed.
>
> On Wed, 19 Aug 2015 10:19:04 +0530
> Archit Taneja <architt@xxxxxxxxxxxxxx> wrote:
>
> > Add DT bindings document for the Qualcomm NAND controller driver.
> >
> > Cc: devicetree@xxxxxxxxxxxxxxx
> >
> > v4:
> > - No changes
> >
> > v3:
> > - Don't use '0x' when specifying nand controller address space
> > - Add optional property for on-flash bbt usage
> >
> > Acked-by: Andy Gross <agross@xxxxxxxxxxxxxx>
> > Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
> > ---
> >   .../devicetree/bindings/mtd/qcom_nandc.txt         | 49 ++++++++++++++++++++++
> >   1 file changed, 49 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> >
> > diff --git a/Documentation/devicetree/bindings/mtd/qcom_nandc.txt b/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> > new file mode 100644
> > index 0000000..1de4643
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> > @@ -0,0 +1,49 @@
> > +* Qualcomm NAND controller
> > +
> > +Required properties:
> > +- compatible:		should be "qcom,ebi2-nand" for IPQ806x
> > +- reg:			MMIO address range
> > +- clocks:		must contain core clock and always on clock
> > +- clock-names:		must contain "core" for the core clock and "aon" for the
> > +			always on clock
> > +- dmas:			DMA specifier, consisting of a phandle to the ADM DMA
> > +			controller node and the channel number to be used for
> > +			NAND. Refer to dma.txt and qcom_adm.txt for more details
> > +- dma-names:		must be "rxtx"
> > +- qcom,cmd-crci:	must contain the ADM command type CRCI block instance
> > +			number specified for the NAND controller on the given
> > +			platform
> > +- qcom,data-crci:	must contain the ADM data type CRCI block instance
> > +			number specified for the NAND controller on the given
> > +			platform
> > +
> > +Optional properties:
> > +- nand-bus-width:	bus width. Must be 8 or 16. If not present, 8 is chosen
> > +			as default
> > +
> > +- nand-ecc-strength:	number of bits to correct per ECC step. Must be 4 or 8
> > +			bits. If not present, 4 is chosen as default
> > +- nand-on-flash-bbt:	Create/use on-flash bad block table
> > +
> > +The device tree may optionally contain sub-nodes describing partitions of the
> > +address space. See partition.txt for more detail.
> > +
> > +Example:
> > +
> > +nand@1ac00000 {
> > +	compatible = "qcom,ebi2-nandc";
> > +	reg = <0x1ac00000 0x800>;
> > +
> > +	clocks = <&gcc EBI2_CLK>,
> > +		 <&gcc EBI2_AON_CLK>;
> > +	clock-names = "core", "aon";
> > +
> > +	dmas = <&adm_dma 3>;
> > +	dma-names = "rxtx";
> > +	qcom,cmd-crci = <15>;
> > +	qcom,data-crci = <3>;
> > +
> > +	partition@0 {
> > +	...
> > +	};
> > +};
>
>
> According to the registers layout defined in your driver, your NAND
> controller can address multiple chips (NAND_DEV_SEL register). Since DT
> bindings are supposed to be as stable as possible, I would recommend
> separating the NAND controller and NAND chip declaration (as done here
> [1] and here [2]).

Yes, the controller does support multiple chips, but the driver only
supports one chip for now.

I'll make changes such that the driver works in accordance to the DT
bindings format you shared.

Thanks for the review.

Archit


> Best Regards,
>
> Boris
>
> [1]http://lxr.free-electrons.com/source/Documentation/devicetree/bindings/mtd/brcm,brcmnand.txt
> [2]http://lxr.free-electrons.com/source/Documentation/devicetree/bindings/mtd/sunxi-nand.txt

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