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From: "Michael Walle" <mwalle@kernel.org>
To: "Pratyush Yadav" <pratyush@kernel.org>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>
Cc: "Takahiro Kuwano" <takahiro.kuwano@infineon.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Sean Anderson" <sean.anderson@linux.dev>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	"Steam Lin" <STLin2@winbond.com>, <linux-mtd@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v4 16/27] mtd: spi-nor: Create a local SR cache
Date: Wed, 06 May 2026 10:51:20 +0200	[thread overview]
Message-ID: <DIBGRTZ3BUEE.1GIAWVBNNXUY5@kernel.org> (raw)
In-Reply-To: <2vxz7bph25qx.fsf@kernel.org>

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On Tue May 5, 2026 at 6:14 PM CEST, Pratyush Yadav wrote:
> On Fri, Apr 03 2026, Miquel Raynal wrote:
>
>> In order to be able to generate debugfs output without having to
>> actually reach the flash, create a SPI NOR local cache of the status
>> registers. What matters in our case are all the bits related to sector
>> locking. As such, in order to make it clear that this cache is not
>> intended to be used anywhere else, we zero the irrelevant bits.
>>
>> The cache is initialized once during the early init, and then maintained
>> every time the write protection scheme is updated.
>
> What is the reason for doing so? Do the reads have side effects?

I don't like that a debugfs read will issue a SPI transaction, at
least not these informational files.

If we ever want to access the registers in the flash, we should have
a separate debugfs file/interface.

-michael

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  reply	other threads:[~2026-05-06  8:51 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-03 16:09 [PATCH v4 00/27] mtd: spi-nor: Enhance software protection Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 01/27] mtd: spi-nor: Drop duplicate Kconfig dependency Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 02/27] mtd: spi-nor: debugfs: Fix the flags list Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 03/27] mtd: spi-nor: swp: Improve locking user experience Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 04/27] mtd: spi-nor: Improve opcodes documentation Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 05/27] mtd: spi-nor: debugfs: Align variable access with the rest of the file Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 06/27] mtd: spi-nor: debugfs: Enhance output Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 07/27] mtd: spi-nor: swp: Explain the MEMLOCK ioctl implementation behaviour Miquel Raynal
2026-05-05 15:40   ` Pratyush Yadav
2026-05-06  8:42     ` Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 08/27] mtd: spi-nor: swp: Clarify a comment Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 09/27] mtd: spi-nor: swp: Use a pointer for SR instead of a single byte Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 10/27] mtd: spi-nor: swp: Create a helper that writes SR, CR and checks Miquel Raynal
2026-05-05 16:05   ` Pratyush Yadav
2026-05-06  8:57     ` Miquel Raynal
2026-05-06  9:06     ` Michael Walle
2026-05-06  9:54       ` Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 11/27] mtd: spi-nor: swp: Rename a mask Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 12/27] mtd: spi-nor: swp: Create a TB intermediate variable Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 13/27] mtd: spi-nor: swp: Create helpers for building the SR register Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 14/27] mtd: spi-nor: swp: Simplify checking the locked/unlocked range Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 15/27] mtd: spi-nor: swp: Cosmetic changes Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 16/27] mtd: spi-nor: Create a local SR cache Miquel Raynal
2026-05-05 16:14   ` Pratyush Yadav
2026-05-06  8:51     ` Michael Walle [this message]
2026-05-06  8:59       ` Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 17/27] mtd: spi-nor: debugfs: Add locking support Miquel Raynal
2026-04-10  4:39   ` Takahiro.Kuwano
2026-04-27 13:39     ` Miquel Raynal
2026-04-27 16:11       ` Pratyush Yadav
2026-04-28  7:56         ` Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 18/27] mtd: spi-nor: debugfs: Add a locked sectors map Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 19/27] mtd: spi-nor: Add steps for testing locking support Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 20/27] mtd: spi-nor: swp: Add support for the complement feature Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 21/27] mtd: spi-nor: Add steps for testing locking with CMP Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 22/27] mtd: spi-nor: winbond: Add W25H512NWxxAM CMP locking support Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 23/27] mtd: spi-nor: winbond: Add W25H01NWxxAM " Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 24/27] mtd: spi-nor: winbond: Add W25H02NWxxAM " Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 25/27] mtd: spi-nor: winbond: Add W25H01NWxxIQ " Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 26/27] mtd: spi-nor: winbond: Add W25Q01NWxxIM " Miquel Raynal
2026-04-03 16:09 ` [PATCH v4 27/27] mtd: spi-nor: winbond: Add W25Q02NWxxIM " Miquel Raynal

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