Re: [PATCH v2 12/25] dt-bindings: qcom_nandc: QPIC NAND documentation
From: Boris Brezillon
Date: Fri Aug 04 2017 - 08:45:46 EST
On Mon, 31 Jul 2017 21:35:57 +0530
Abhishek Sahu <absahu@xxxxxxxxxxxxxx> wrote:
> On 2017-07-26 00:13, Abhishek Sahu wrote:
> > On 2017-07-25 00:47, Rob Herring wrote:
> >> On Wed, Jul 19, 2017 at 05:18:00PM +0530, Abhishek Sahu wrote:
> >>> 1. QPIC NAND will use compatible string "qcom,qpic-nandc-v1.4.0"
> >>> 2. QPIC NAND will 3 BAM channels: command, data tx and data rx
> >>> while EBI2 NAND uses only single ADM channel.
> >>> 3. CRCI is only required for ADM DMA and its not required for
> >>> QPIC NAND.
> >>> Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
> >>> ---
> >>> .../devicetree/bindings/mtd/qcom_nandc.txt | 54
> >>> ++++++++++++++++++++--
> >>> 1 file changed, 51 insertions(+), 3 deletions(-)
> >>> diff --git a/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> >>> b/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> >>> index b24adfe..8efaeb0 100644
> >>> --- a/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> >>> +++ b/Documentation/devicetree/bindings/mtd/qcom_nandc.txt
> >>> @@ -1,13 +1,15 @@
> >>> * Qualcomm NAND controller
> >>> Required properties:
> >>> -- compatible: should be "qcom,ebi2-nandc" - EBI2 NAND which uses
> >>> ADM
> >>> - DMA like IPQ8064.
> >>> -
> >>> +- compatible: must be one of the following:
> >>> + * "qcom,ebi2-nandc" - EBI2 NAND which uses ADM DMA like IPQ8064.
> >>> + * "qcom,qpic-nandc-v1.4.0" - QPIC NAND v1.4.0 which uses BAM DMA
> >>> like IPQ4019.
> >> Looks like you have 2 SoCs and 2 versions of h/w. Use SoC specific
> >> compatible strings.
> > We have 3 versions of NAND HW currently.
> > EBI2,
> > QPIC version 1.4.0
> > QPIC version 1.5.0
> > and multiple Qualcomm SoCs which use any one of these.
> > The original plan was to have compatible string for NAND version since
> > same NAND hardware is being in different SoC and SoC dtsi will simply
> > use its NAND version compatible string like other Qualcomm hardwares
> > http://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> > http://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
> Following are the partial list for NAND controller and supported
> EBI2: IPQ8064, APQ8064, MSM7xx, MDM9x15
> QPIC v1.4.0 MDM9x25, MDM9x35, MDM9x45, IPQ4019
> QPIC v1.5.0 MDM9x55, IPQ8074
> so could we use NAND controller specific compatible strings instead of
> since it will easy to maintain?
Nope, though you can re-use the compatible of an old SoC for new SoCs
if the IP did not change.
- EBI2: compatible = "qcom,ipq8064"
- QPIC 1.4: compatible = "qcom,mdm9x25"
- QPIC 1.5: compatible = "qcom,mdm9x55"
Note that we usually pick the oldest SoC that started embedding an IP
when choosing the compatible. So my suggestion assumes IPQ8064 is older
than APQ8064, MSM7xx and MDM9x15.