From: Marek Vasut <marex@denx.de>
To: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Cc: nicolas.ferre@atmel.com, broonie@kernel.org,
linux-spi@vger.kernel.org, dwmw2@infradead.org,
computersforpeace@gmail.com, zajec5@gmail.com,
beanhuo@micron.com, juhosg@openwrt.org, shijie.huang@intel.com,
ben@decadent.org.uk, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com,
ijc+devicetree@hellion.org.uk, galak@codeaurora.org,
linux-mtd@lists.infradead.org
Subject: Re: [PATCH linux-next v5 3/5] mtd: spi-nor: allow to tune the number of dummy cycles
Date: Wed, 26 Aug 2015 16:39:02 +0200 [thread overview]
Message-ID: <201508261639.02377.marex@denx.de> (raw)
In-Reply-To: <4324f398c0e69e3057e7da6a1a3e0328b44f224f.1440580764.git.cyrille.pitchen@atmel.com>
On Wednesday, August 26, 2015 at 02:30:25 PM, Cyrille Pitchen wrote:
> The number of dummy cycles used during Fast Read commands can be reduced
> to improve transfer performances. Each manufacturer has a dedicated set of
> registers to provide the memory with the exact number of dummy cycles it
> should expect. Both the memory and the (Q)SPI controller must agree on
> this number of dummy cycles.
>
> The number of dummy cycles can be found into the memory datasheet and
> mostly depends on the SPI clock frequency, the Fast Read op code and the
> Single/Dual Data Rate mode.
>
> Probing JEDEC Serial Flash Discoverable Parameters (SFDP) tables would
> only provide the driver with a high enough number of dummy cycles for each
> Fast Read command to be used for all clock frequencies: this solution
> would not be optimized.
>
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Acked-by: Marek Vasut <marex@denx.de>
Best regards,
Marek Vasut
next prev parent reply other threads:[~2015-08-26 14:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-26 12:30 [PATCH linux-next v5 0/5] add driver for Atmel QSPI controller Cyrille Pitchen
2015-08-26 12:30 ` [PATCH linux-next v5 1/5] mtd: spi-nor: notify (Q)SPI controller about protocol change Cyrille Pitchen
2015-08-26 14:02 ` Jonas Gorski
2015-08-27 9:51 ` Cyrille Pitchen
2015-08-31 19:22 ` Jonas Gorski
2015-09-08 16:20 ` Cyrille Pitchen
2015-09-08 16:29 ` Marek Vasut
2015-08-26 12:30 ` [PATCH linux-next v5 2/5] Documentation: mtd: add a DT property to set the number of dummy cycles Cyrille Pitchen
2015-08-26 12:30 ` [PATCH linux-next v5 3/5] mtd: spi-nor: allow to tune " Cyrille Pitchen
2015-08-26 14:39 ` Marek Vasut [this message]
2015-08-26 12:30 ` [PATCH linux-next v5 4/5] Documentation: atmel-quadspi: add binding file for Atmel QSPI driver Cyrille Pitchen
2015-09-08 23:29 ` Rob Herring
2015-08-26 12:30 ` [PATCH linux-next v5 5/5] mtd: atmel-quadspi: add driver for Atmel QSPI controller Cyrille Pitchen
2015-08-26 16:26 ` Marek Vasut
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