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From: "Arnd Bergmann" <arnd@arndb.de>
To: "Frieder Schrempf" <frieder@fris.de>,
	"Peng Fan" <peng.fan@nxp.com>,
	"Pankaj Gupta" <pankaj.gupta@nxp.com>,
	linux-arm-kernel@lists.infradead.org,
	"Conor Dooley" <conor+dt@kernel.org>,
	devicetree@vger.kernel.org, imx@lists.linux.dev,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	linux-kernel@vger.kernel.org, "Rob Herring" <robh@kernel.org>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Srinivas Kandagatla" <srinivas.kandagatla@linaro.org>
Cc: "Frieder Schrempf" <frieder.schrempf@kontron.de>,
	"Fabio Estevam" <festevam@gmail.com>,
	"Frank Li" <Frank.Li@nxp.com>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Pengutronix Kernel Team" <kernel@pengutronix.de>,
	"Rafał Miłecki" <rafal@milecki.pl>,
	"Shengjiu Wang" <shengjiu.wang@nxp.com>,
	"Shenwei Wang" <shenwei.wang@nxp.com>,
	"Xu Yang" <xu.yang_2@nxp.com>,
	"Yoshihiro Shimoda" <yoshihiro.shimoda.uh@renesas.com>
Subject: Re: [RFC PATCH 0/5] Add NVMEM driver for i.MX93 OTP access through ELE
Date: Tue, 22 Apr 2025 08:40:51 +0200	[thread overview]
Message-ID: <6ee90a9e-cfa0-45f5-8036-bf04cb19db46@app.fastmail.com> (raw)
In-Reply-To: <20250416142715.1042363-1-frieder@fris.de>

On Wed, Apr 16, 2025, at 16:26, Frieder Schrempf wrote:

> Therefore I implemented a simple driver that uses the ELE S400 API only, as the
> FSB access (1) doesn't provide any benefits except for that it doesn't depend
> on the ELE firmware being available. This is used by us downstream.
>
> For the upstream solution I would like to have some feedback on how to move
> on:
>
> 1. switch imx-ocotp-ele.c to use ELE API exclusively
>    -> this will create a hard dependency on the ELE firmware/driver 
> being available

Could this cause problems for real-time Linux users? Usually going
through a firmware driver adds more latency than doing the thing
from Linux directly, and the firmware is usually not preemptable.

In particular, programming a one-time fuse is likely a slow
operation in hardware, so it may still be necessary to support
both methods if there are users that need to update the fuses
on real-time systems.

     Arnd


  parent reply	other threads:[~2025-04-22  6:43 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-16 14:26 [RFC PATCH 0/5] Add NVMEM driver for i.MX93 OTP access through ELE Frieder Schrempf
2025-04-16 14:26 ` [RFC PATCH 1/5] firmware: imx: ele: Add API functions for OCOTP fuse access Frieder Schrempf
2025-04-16 14:26 ` [RFC PATCH 2/5] nvmem: Add i.MX OCOTP fuse driver using ELE S400 API Frieder Schrempf
2025-04-16 14:26 ` [RFC PATCH 3/5] arm64: dts: imx93: Add node for EdgeLock Enclave (ELE) firmware driver Frieder Schrempf
2025-04-16 14:26 ` [RFC PATCH 4/5] arm64: dts: imx93: Add node for OCOTP S400 NVMEM driver Frieder Schrempf
2025-04-16 14:26 ` [RFC PATCH 5/5] arm64: dts: imx93-kontron: Add DMA memory region for ELE firmware Frieder Schrempf
2025-04-22  6:30 ` [RFC PATCH 0/5] Add NVMEM driver for i.MX93 OTP access through ELE Peng Fan
2025-04-22  7:33   ` Frieder Schrempf
2025-04-22  6:40 ` Arnd Bergmann [this message]
2025-04-22  7:37   ` Frieder Schrempf

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