Re: [PATCH v2 0/2] mtd: devices: Qualcomm SCM storage support

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Junhao Xie <bigfoot@radxa.com>
Cc: Bjorn Andersson <andersson@kernel.org>,
	 Konrad Dybcio <konradybcio@kernel.org>,
	 Richard Weinberger <richard@nod.at>,
	 Vignesh Raghavendra <vigneshr@ti.com>,
	 linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 linux-mtd@lists.infradead.org,  Xilin Wu <sophon@radxa.com>
Subject: Re: [PATCH v2 0/2] mtd: devices: Qualcomm SCM storage support
Date: Fri, 30 Jan 2026 15:10:38 +0100	[thread overview]
Message-ID: <87ecn7jin5.fsf@bootlin.com> (raw)
In-Reply-To: <86F97239DB3D962C+98826904-6649-4c19-815d-73003c046c14@radxa.com> (Junhao Xie's message of "Fri, 30 Jan 2026 21:39:48 +0800")

Hi,

>> I don't believe you answered my question regarding how to access this
>> interface from the kernel. On many of these devices we can find the MAC
>> addresses of the system in the "DPP" partition. Do you have any ideas
>> about how we could access this from within the kernel?
>>
>> Regards,
>> Bjorn
>
> I agree with your point. I will add a module param in v3 for default
> read-only mode. e.g.: /sys/module/qcom_scm_storage/parameters/allow_write
>
> For something like the "DPP" partition, I think it's better to access it
> from userspace than from kernel.

If it's a MAC address that you are accessing, direct userspace does not
sound like a good fit. If I may, NVMEM cells are there exactly for this
purpose: identifying the content of a subpart of a storage device in a
storage agnostic way. The NVMEM cells are made available to in-kernel
drivers (ie. network devices have all the infrastructure to get the MAC
address from there) and their content is also exposed to userspace
through sysfs now.

Thanks,
Miquèl

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