linux-kernel - Re: [PATCH v2 1/3] mtd: spi-nor: macronix: Drop the redundant flash info fields

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Message-ID: <da58fc81-3c99-4951-85bc-e3c139283b5a@roeck-us.net>
Date: Sun, 8 Jun 2025 18:13:09 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Pratyush Yadav <pratyush@...nel.org>
Cc: Cheng Ming Lin <linchengming884@...il.com>, tudor.ambarus@...aro.org,
 mwalle@...nel.org, miquel.raynal@...tlin.com, richard@....at,
 vigneshr@...com, linux-mtd@...ts.infradead.org,
 linux-kernel@...r.kernel.org, alvinzhou@...c.com.tw, leoyu@...c.com.tw,
 Cheng Ming Lin <chengminglin@...c.com.tw>
Subject: Re: [PATCH v2 1/3] mtd: spi-nor: macronix: Drop the redundant flash
 info fields

On 6/8/25 05:53, Pratyush Yadav wrote:
> On Sat, Jun 07 2025, Guenter Roeck wrote:
> 
>> Hi,
>>
>> On Mon, Apr 07, 2025 at 03:53:58PM +0800, Cheng Ming Lin wrote:
>>> From: Cheng Ming Lin <chengminglin@...c.com.tw>
>>>
>>> Many flash devices share the same ID but have different part numbers.
>>> To avoid confusion, the part number field is removed.
>>>
>>> Additionally, since SFDP already provides size information and
>>> functionality covered by no_sfdp_flags, these fields are also removed.
>>>
>>> Furthermore, when 4-byte address instruction table is available,
>>> the SPI_NOR_4B_OPCODES flag is no longer needed and is removed.
>>>
>>> Signed-off-by: Cheng Ming Lin <chengminglin@...c.com.tw>
>>> Acked-by: Tudor Ambarus <tudor.ambarus@...aro.org>
>>
>> With this patch in place, some of my qemu tests no longer recognize the
>> flash chips (MX25L25635E/F). Do you have a suggestion on how to handle
>> this other than avoiding Macronix flash chips when working with qemu ?
> 
> Could you share some logs? Does the flash fail to detect, or does the
> SFDP-based probing fail? Since this is qemu, it would be even better if
> you can share a setup/reproduction guide. I have been meaning to set up
> qemu for SPI NOR testing for some time now, but never got around to
> figuring it out.
> 

I suspect that the SFDP data for the affected flashes is incorrect in qemu.
Since this is very likely a qemu problem, I'll just configure different flash
chips when running affected tests.

For reference, here is a sample qemu command line.

qemu-system-arm -M supermicro-x11spi-bmc,fmc-model=n25q256a13,spi-model=n25q256a13 \
	-kernel arch/arm/boot/zImage -no-reboot -snapshot -audio none \
	-drive file=/tmp/flash,format=raw,if=mtd -nic user \
	--append "root=/dev/mtdblock0 rootwait console=ttyS4,115200 earlycon=uart8250,mmio32,0x1e784000,115200n8" \
	-dtb arch/arm/boot/dts/aspeed/aspeed-bmc-supermicro-x11spi.dtb \
	-nographic -monitor null -serial stdio

This is with aspeed_g5_defconfig. In this example, ",fmc-model=n25q256a13,spi-model=n25q256a13"
is used to override the default flash model (MX25L25635E) because it longer works after
this patch. Normally that should not be required, but it is useful to test support
for different flash chips.

Guenter