From: Pratyush Yadav <p.yadav@ti.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Vignesh Raghavendra <vigneshr@ti.com>,
Tudor Ambarus <tudor.ambarus@microchip.com>,
Richard Weinberger <richard@nod.at>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Sekhar Nori <nsekhar@ti.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
MTD Maling List <linux-mtd@lists.infradead.org>,
Boris Brezillon <boris.brezillon@collabora.com>
Subject: Re: [PATCH v2 01/11] dt-bindings: spi: allow expressing DTR capability
Date: Mon, 2 Mar 2020 15:23:45 +0530 [thread overview]
Message-ID: <20200302095343.3yec6inur52vx6bg@ti.com> (raw)
In-Reply-To: <CAMuHMdV_1RfGFgDjJYzAnGd_x57zSwjZd8si=UTPp8ksgdwYGA@mail.gmail.com>
On 27/02/20 06:03PM, Geert Uytterhoeven wrote:
> Hi Mark,
>
> On Thu, Feb 27, 2020 at 5:44 PM Mark Brown <broonie@kernel.org> wrote:
> > On Thu, Feb 27, 2020 at 05:40:31PM +0100, Geert Uytterhoeven wrote:
> > > On Thu, Feb 27, 2020 at 5:28 PM Mark Brown <broonie@kernel.org> wrote:
> > > > It's what we do for other properties, and if this is anything like the
> > > > other things adding extra wiring you can't assume that the ability to
> > > > use the feature for TX implies RX.
> >
> > > Double Transfer Rate uses the same wire.
> >
> > But is it still on either the TX or RX signals?
>
> E.g. good old Spansion S25FL512S supports single/dual/quad DDR, but
> apparently only for read, not write.
> Other FLASHes may support both directions. I guess.
The flash datasheet says under section 9.4 (Read Memory Array Commands):
Some commands transfer address and data on both the rising edge and
falling edge of SCK. These are called Double Data Rate (DDR) commands.
Since the address is transferred in DDR mode, both Tx and Rx signals use
DDR.
So, unless we have a flash that supports a mode like 1S-1S-8D, we don't
really need two properties.
--
Regards,
Pratyush Yadav
Texas Instruments India
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next prev parent reply other threads:[~2020-03-02 9:54 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 9:36 [PATCH v2 00/11] mtd: spi-nor: add xSPI Octal DTR support Pratyush Yadav
2020-02-26 9:36 ` [PATCH v2 01/11] dt-bindings: spi: allow expressing DTR capability Pratyush Yadav
2020-02-27 16:11 ` Boris Brezillon
2020-02-27 16:28 ` Mark Brown
2020-02-27 16:40 ` Geert Uytterhoeven
2020-02-27 16:44 ` Mark Brown
2020-02-27 17:03 ` Geert Uytterhoeven
2020-03-02 9:53 ` Pratyush Yadav [this message]
2020-02-27 17:06 ` Boris Brezillon
2020-02-27 16:29 ` Geert Uytterhoeven
2020-02-28 9:46 ` Pratyush Yadav
2020-02-26 9:36 ` [PATCH v2 02/11] spi: set mode bits for "spi-rx-dtr" and "spi-tx-dtr" Pratyush Yadav
2020-02-27 16:23 ` Boris Brezillon
2020-03-02 9:48 ` Pratyush Yadav
2020-03-02 10:20 ` Boris Brezillon
2020-02-26 9:36 ` [PATCH v2 03/11] spi: spi-mem: allow specifying whether an op is DTR or not Pratyush Yadav
2020-02-27 16:36 ` Boris Brezillon
2020-02-26 9:36 ` [PATCH v2 04/11] spi: spi-mem: allow specifying a command's extension Pratyush Yadav
2020-02-27 16:44 ` Boris Brezillon
2020-02-28 9:41 ` Pratyush Yadav
2020-02-26 9:36 ` [PATCH v2 05/11] spi: cadence-quadspi: Add support for octal DTR flashes Pratyush Yadav
2020-02-26 9:36 ` [PATCH v2 06/11] mtd: spi-nor: add support for DTR protocol Pratyush Yadav
2020-02-27 16:58 ` Boris Brezillon
2020-02-28 9:36 ` Pratyush Yadav
2020-02-28 10:53 ` Boris Brezillon
2020-02-28 12:07 ` Pratyush Yadav
2020-02-28 13:18 ` Boris Brezillon
2020-02-26 9:36 ` [PATCH v2 07/11] mtd: spi-nor: get command opcode extension type from BFPT Pratyush Yadav
2020-02-26 9:37 ` [PATCH v2 08/11] mtd: spi-nor: parse xSPI Profile 1.0 table Pratyush Yadav
2020-02-26 9:37 ` [PATCH v2 09/11] mtd: spi-nor: use dummy cycle and address width info from SFDP Pratyush Yadav
2020-02-26 9:37 ` [PATCH v2 10/11] mtd: spi-nor: enable octal DTR mode when possible Pratyush Yadav
2020-02-26 9:37 ` [PATCH v2 11/11] mtd: spi-nor: add support for Cypress Semper flash Pratyush Yadav
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