From: Boris Brezillon <boris.brezillon@collabora.com>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org, Vignesh Raghavendra <vigneshr@ti.com>,
Tudor Ambarus <tudor.ambarus@microchip.com>,
Richard Weinberger <richard@nod.at>, Sekhar Nori <nsekhar@ti.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
linux-spi@vger.kernel.org, Mark Brown <broonie@kernel.org>,
linux-mtd@lists.infradead.org,
Miquel Raynal <miquel.raynal@bootlin.com>
Subject: Re: [PATCH v2 06/11] mtd: spi-nor: add support for DTR protocol
Date: Thu, 27 Feb 2020 17:58:41 +0100 [thread overview]
Message-ID: <20200227175841.51435e3f@collabora.com> (raw)
In-Reply-To: <20200226093703.19765-7-p.yadav@ti.com>
On Wed, 26 Feb 2020 15:06:58 +0530
Pratyush Yadav <p.yadav@ti.com> wrote:
> Double Transfer Rate (DTR) is SPI protocol in which data is transferred
> on each clock edge as opposed to on each clock cycle. Make
> framework-level changes to allow supporting flashes in DTR mode.
>
> Right now, mixed DTR modes are not supported. So, for example a mode
> like 4S-4D-4D will not work. All phases need to be either DTR or STR.
Didn't go deep into the patch but at first glance you don't seem to
extend the framework to support stateful modes as I tried to do here
[1]. That's really something we should address before considering
supporting xD-xD-xD modes, unless the SPI-NOR only supports one
stateful mode. If we don't do that first, we might face all sort of
unpleasant issues:
* kexec not working correctly because the previous kernel left the NOR
in an unknown state
* suspend/resume not working properly
* linux not booting properly because the bootloader left the device in
its non-default mode
* ...
[1]https://patchwork.kernel.org/cover/10638055/
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next prev parent reply other threads:[~2020-02-27 16:59 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
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 [this message]
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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