From: Rob Herring <robh@kernel.org>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>,
Vignesh Raghavendra <vigneshr@ti.com>,
Tudor Ambarus <Tudor.Ambarus@microchip.com>,
Pratyush Yadav <p.yadav@ti.com>, Michael Walle <michael@walle.cc>,
linux-mtd@lists.infradead.org, Michal Simek <monstr@monstr.eu>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
devicetree@vger.kernel.org, Mark Brown <broonie@kernel.org>,
linux-spi@vger.kernel.org
Subject: Re: [PATCH v4 2/3] spi: dt-bindings: Describe stacked/parallel memories modes
Date: Tue, 14 Dec 2021 11:32:56 -0600 [thread overview]
Message-ID: <YbjVSNAC8M5Y1nHp@robh.at.kernel.org> (raw)
In-Reply-To: <20211210201039.729961-3-miquel.raynal@bootlin.com>
On Fri, Dec 10, 2021 at 09:10:38PM +0100, Miquel Raynal wrote:
> Describe two new memories modes:
> - A stacked mode when the bus is common but the address space extended
> with an additinals wires.
> - A parallel mode with parallel busses accessing parallel flashes where
> the data is spread.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
> .../bindings/spi/spi-peripheral-props.yaml | 29 +++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
> index 5dd209206e88..4194fee8f556 100644
> --- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
> +++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
> @@ -82,6 +82,35 @@ properties:
> description:
> Delay, in microseconds, after a write transfer.
>
> + stacked-memories:
> + $ref: /schemas/types.yaml#/definitions/uint64-matrix
matrix or...
> + description: Several SPI memories can be wired in stacked mode.
> + This basically means that either a device features several chip
> + selects, or that different devices must be seen as a single
> + bigger chip. This basically doubles (or more) the total address
> + space with only a single additional wire, while still needing
> + to repeat the commands when crossing a chip boundary. The size of
> + each chip should be provided as members of the array.
array?
Sounds like an array from the description as there is only 1 element,
the size.
> + minItems: 2
> + maxItems: 2
> + items:
> + maxItems: 1
This says you can only have 2 64-bit entries. Probably not what you
want. This looks like a case for a maxItems 'should be enough for now'
type of value.
> +
> + parallel-memories:
> + $ref: /schemas/types.yaml#/definitions/uint64-matrix
> + description: Several SPI memories can be wired in parallel mode.
> + The devices are physically on a different buses but will always
> + act synchronously as each data word is spread across the
> + different memories (eg. even bits are stored in one memory, odd
> + bits in the other). This basically doubles the address space and
> + the throughput while greatly complexifying the wiring because as
> + many busses as devices must be wired. The size of each chip should
> + be provided as members of the array.
> + minItems: 2
> + maxItems: 2
> + items:
> + maxItems: 1
> +
> # The controller specific properties go here.
> allOf:
> - $ref: cdns,qspi-nor-peripheral-props.yaml#
> --
> 2.27.0
>
>
next prev parent reply other threads:[~2021-12-14 17:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-10 20:10 [PATCH v4 0/3] Stacked/parallel memories bindings Miquel Raynal
2021-12-10 20:10 ` [PATCH v4 1/3] dt-bindings: mtd: spi-nor: Allow two CS per device Miquel Raynal
2021-12-10 20:10 ` [PATCH v4 2/3] spi: dt-bindings: Describe stacked/parallel memories modes Miquel Raynal
2021-12-14 17:32 ` Rob Herring [this message]
2021-12-16 15:02 ` Miquel Raynal
2022-01-10 8:31 ` Miquel Raynal
2022-01-21 15:54 ` Rob Herring
2022-01-26 11:18 ` Miquel Raynal
2021-12-14 19:44 ` Pratyush Yadav
2021-12-16 16:25 ` Miquel Raynal
2021-12-17 12:39 ` Pratyush Yadav
2021-12-17 12:58 ` Miquel Raynal
2021-12-10 20:10 ` [PATCH v4 3/3] spi: dt-bindings: Add an example with two stacked flashes Miquel Raynal
2021-12-14 17:37 ` Rob Herring
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