linux-kernel - Re: [PATCH v5 2/2] nvmem: imx-ocotp-ele: Support accessing controller for i.MX9

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Message-ID: <4956524.GXAFRqVoOG@steina-w>
Date: Mon, 13 Jan 2025 13:16:48 +0100
From: Alexander Stein <alexander.stein@...tq-group.com>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>, Peng Fan <peng.fan@....com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam <festevam@...il.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/2] nvmem: imx-ocotp-ele: Support accessing controller for i.MX9

Hi,

Am Samstag, 11. Januar 2025, 13:41:58 CET schrieb Peng Fan:
> > Subject: Re: [PATCH v5 2/2] nvmem: imx-ocotp-ele: Support accessing
> > controller for i.MX9
> > 
> > Hi,
> > 
> > Am Donnerstag, 9. Januar 2025, 04:34:18 CET schrieb Peng Fan:
> > > On Wed, Jan 08, 2025 at 11:15:40AM +0100, Alexander Stein wrote:
> > > >Hi Peng,
> > > >
> > > >Am Mittwoch, 8. Januar 2025, 08:00:18 CET schrieb Peng Fan (OSS):
> > > >> From: Peng Fan <peng.fan@....com>
> > > >>
> > > >> i.MX9 OCOTP supports a specific peripheral or function being
> > fused
> > > >> which means disabled, so
> > > >>  - Introduce ocotp_access_gates to be container of efuse gate info
> > > >>  - Iterate all nodes to check accessing permission. If not
> > > >>    allowed to be accessed, detach the node
> > > >>
> > > >> Signed-off-by: Peng Fan <peng.fan@....com>
> > > >> ---
> > > >>  drivers/nvmem/imx-ocotp-ele.c | 172
> > > >> +++++++++++++++++++++++++++++++++++++++++-
> > > >>  1 file changed, 171 insertions(+), 1 deletion(-)
> > > >>
> > > [....]
> > > >> +
> > > >> +	return imx_ele_ocotp_access_control(priv);
> > > >
> > > >In [1] you mentioned devlink should solve the probe order. How
> > does
> > > >this play when the driver is compiled in (e.g. ethernet for NFS boot)
> > > >but this OCOTP driver is just a module?
> > >
> > > OCOTP needs to built in for using devlink. Or the users needs to be
> > > built as module.
> > 
> > I don't like this kind of assumption. Would it make more sense to make
> > CONFIG_NVMEM_IMX_OCOTP_ELE as bool instead of tristate?
> 
> No. Users could setup their own system with this driver build in
> or built related drivers as modules.

Sure, but if the kernel locks/fails/panics while accessing peripherals
just because of the kernel config seems at east very unfortunate to me.
How is someone supposed to analyze/debug this?

> At least for Android GKI, this driver needs to be as module.

Any particular reason this needs to be a module?
Which means any affected driver needs to be a module as well just because if
a DT reference, no? With no means to know which drivers are affected, despite
checking for the DT references manually?

Best regards,
Alexander
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