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

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Message-ID: <6018578.MhkbZ0Pkbq@steina-w>
Date: Wed, 15 Jan 2025 07:56:03 +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 Dienstag, 14. Januar 2025, 09:35:41 CET schrieb Peng Fan:
> > 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?
> 
> Android has a minimal kernel which is controlled by Google.
> Vendors could only built modules based on Google's Image.
> 
> Updating this to y in upstream, means we need to change
> it back to m in NXP downstream android kernel.

Ok, that's an Android thing.

> If you need it built in, you could modify your downstream
> config, right?

I'm not saying I need a built-in. My concern is that a wrong Kconfig will
result in silent errors/lockups.

Best regards,
Alexander
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