From: Pratyush Yadav <p.yadav@ti.com>
To: <Tudor.Ambarus@microchip.com>
Cc: vigneshr@ti.com, sergei.shtylyov@cogentembedded.com,
richard@nod.at, me@yadavpratyush.com, john.garry@huawei.com,
linuxarm@huawei.com, yangyicong@hisilicon.com,
alexander.sverdlin@nokia.com, miquel.raynal@bootlin.com,
linux-mtd@lists.infradead.org
Subject: Re: [PATCH 2/2] mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()
Date: Fri, 3 Jul 2020 16:49:24 +0530 [thread overview]
Message-ID: <20200703111924.tyrvzbbgd7ak53qf@ti.com> (raw)
In-Reply-To: <193b32f7-f56d-4f78-5353-b5d47cbf71d6@microchip.com>
On 02/07/20 11:02AM, Tudor.Ambarus@microchip.com wrote:
> On 6/16/20 4:02 PM, Yicong Yang wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > If the flash's quad mode is enabled, it'll remain in the quad mode when
> > it's removed. If we drive the flash next time in SPI/Dual mode, then
> > problem occurs as the flash's quad enable bit is not cleared.
>
> Please describe the problems that occur. When QE bit is one the flash
> operates in Standard/Dual/Quad SPI modes. WP# and RESET#/HOLD# are
> affected as they change their functionality to IO2 and IO3 when QE
> is 1. Is there anything else?
IIUC if we do anything that introduces a state on the flash, we want to
clear that state up on restore. That's what we (will) do for 8D mode and
for 4-byte addressing mode. Does that not apply here?
> While I find the intention good, there might be some problems here:
> 1/ w25q jvm variants come with QE "fixed" to 1. This probably means
> that QE is not writable, and a writing of QE to zero will be ignored,
> but we have to check.
In that case they shouldn't have a quad_enable() hook, no?
> 2/S25FS128S: CR1NV[1] can set the default power-on state for the
> CR1V[1] to 1, i.e. QE to be set to 1 at power-on by default. The
> logic here complicates a bit, and maybe we'll have to amend the
> patch.
>
> >
> > Disable the quad mode in spi_nor_restore(), the flash will leave
> > quad mode when remove. This will make sure the flash always enter the
> > correct mode when loaded.
> s/correct/ Standard/Dual SPI
>
> Cheers,
> ta
--
Regards,
Pratyush Yadav
Texas Instruments India
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next prev parent reply other threads:[~2020-07-03 11:21 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 13:02 [PATCH 0/2] Add support to Disable the flash quad mode Yicong Yang
2020-06-16 13:02 ` [PATCH 1/2] mtd: spi-nor: Add capability to disable " Yicong Yang
2020-07-02 11:07 ` Tudor.Ambarus
2020-06-16 13:02 ` [PATCH 2/2] mtd: spi-nor: Disable the flash quad mode in spi_nor_restore() Yicong Yang
2020-07-02 11:02 ` Tudor.Ambarus
2020-07-03 11:19 ` Pratyush Yadav [this message]
2020-07-03 11:52 ` Tudor.Ambarus
2020-07-06 6:47 ` Yicong Yang
2020-09-01 6:16 ` Matthias Weißer
2020-09-01 9:48 ` Pratyush Yadav
2020-09-01 10:08 ` Matthias Weißer
2020-09-01 11:11 ` Pratyush Yadav
2020-09-01 11:41 ` Yicong Yang
2020-09-01 14:20 ` Yicong Yang
2020-09-02 7:50 ` Vignesh Raghavendra
2020-09-02 10:12 ` Yicong Yang
2020-09-03 5:59 ` Vignesh Raghavendra
2020-09-04 7:54 ` Yicong Yang
2020-09-04 9:35 ` Matthias Weißer
2020-09-02 12:15 ` Matthias Weißer
2020-09-03 3:03 ` Yicong Yang
2020-09-03 5:33 ` Matthias Weißer
2020-09-04 7:56 ` Yicong Yang
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