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From: Bert Vermeulen <bert@biot.com>
To: David Laight <David.Laight@ACULAB.COM>, Pratyush Yadav <p.yadav@ti.com>
Cc: "vigneshr@ti.com" <vigneshr@ti.com>,
	"tudor.ambarus@microchip.com" <tudor.ambarus@microchip.com>,
	"richard@nod.at" <richard@nod.at>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	"miquel.raynal@bootlin.com" <miquel.raynal@bootlin.com>
Subject: Re: [PATCH] mtd: spi-nor: Fix 3-or-4 address byte mode logic
Date: Sun, 4 Oct 2020 23:12:26 +0200	[thread overview]
Message-ID: <2c7b03eb-58fa-73af-93d7-669bad2e57ef@biot.com> (raw)
In-Reply-To: <1c4ee46115854ce28b17935504f2fc78@AcuMS.aculab.com>

On 10/2/20 9:50 AM, David Laight wrote:
> From: Bert Vermeulen
>> The SoCs I'm dealing with have an SPI_ADDR_SEL pin, indicating whether it
>> should be in 3 or 4-byte mode. The vendor's hacked-up U-Boot sets the mode
>> accordingly, as does their BSP. It seems to me like a misfeature, and I want
>> to just ignore it and do reasonable JEDEC things, but I have the problem
>> that the flash chip can be in 4-byte mode by the time it gets to my spi-nor
>> driver.
> 
> If these are the devices I think they are, can't you read the
> non-volatile config word (bit 0) to find out whether the device
> expects a 3 or 4 byte address and how many 'idle' clocks there
> are before the read data?

I'm working with Realtek RTL838x/RTL839x SoCs. Reading it out is a
pretty convoluted procedure involving different I/O registers depending
on the SoC model.


-- 
Bert Vermeulen
bert@biot.com

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  reply	other threads:[~2020-10-04 21:13 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 23:56 [PATCH] mtd: spi-nor: Fix 3-or-4 address byte mode logic Bert Vermeulen
2020-10-01  6:34 ` Pratyush Yadav
2020-10-01 14:15   ` Tudor.Ambarus
2020-10-01 22:22   ` Bert Vermeulen
2020-10-02  7:50     ` David Laight
2020-10-04 21:12       ` Bert Vermeulen [this message]
2020-10-04 21:36         ` David Laight
2020-10-06 23:19     ` Joel Stanley
2020-10-06 11:03   ` Tudor.Ambarus
2020-10-06 11:19     ` Tudor.Ambarus
2020-10-06 11:40       ` Pratyush Yadav

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