linux-kernel - Re: [PATCH] mtd: spi-nor: micron-st: Add n25q064a WP support

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Message-ID: <454deacb-88cc-4ab0-80b4-006d863a56d2@linaro.org>
Date: Tue, 30 Jul 2024 12:33:00 +0100
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Michael Walle <mwalle@...nel.org>,
 Brian Norris <computersforpeace@...il.com>, linux-mtd@...ts.infradead.org
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
 Pratyush Yadav <pratyush@...nel.org>, Richard Weinberger <richard@....at>,
 Vignesh Raghavendra <vigneshr@...com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: spi-nor: micron-st: Add n25q064a WP support

Hi, Brian,

On 7/30/24 7:51 AM, Michael Walle wrote:
> Hi,
> 
> On Fri Jul 26, 2024 at 8:58 PM CEST, Brian Norris wrote:
>> These flash chips are used on Google / TP-Link / ASUS OnHub devices, and
>> OnHub devices are write-protected by default (same as any other
>> ChromeOS/Chromebook system). I've referred to datasheets, and tested on
>> OnHub devices.
> 
> Out of curiosity, there is also a hardware write protect switch
> somehow, right? At least that's my understanding how verify boot
> works.
> 
>>
>> Signed-off-by: Brian Norris <computersforpeace@...il.com>
> 
> This looks good:
> Reviewed-by: Michael Walle <mwalle@...nel.org>
> 
> But could you have a look whether this flash supports SFDP.
> According to the datasheet it looks like it does. In that case,
> could you please dump it according to:
> https://docs.kernel.org/driver-api/mtd/spi-nor.html

This would help getting rid of the no_sfdp_flags and size from the flash
definition. Another reason is that the SFDP dump can help us
differentiate between flavors of the same flash, if it'll ever be the
case, and help us keep backward compatibility.

Also, if you care, would be good to extend the SPI NOR documentation on
how one shall test the Block Protection.

Cheers,
ta