linux-kernel - Re: [PATCH v4 2/3] i2c: tegra: make reset an optional property

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aEsf7Ml__JE1ixQX@surfacebook.localdomain>
Date: Thu, 12 Jun 2025 21:43:56 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Akhil R <akhilrajeev@...dia.com>
Cc: andriy.shevchenko@...ux.intel.com, andi.shyti@...nel.org,
	conor+dt@...nel.org, devicetree@...r.kernel.org, digetx@...il.com,
	jonathanh@...dia.com, krzk+dt@...nel.org, ldewangan@...dia.com,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org, p.zabel@...gutronix.de,
	robh@...nel.org, thierry.reding@...il.com
Subject: Re: [PATCH v4 2/3] i2c: tegra: make reset an optional property

Thu, Jun 12, 2025 at 09:03:38PM +0530, Akhil R kirjoitti:
> On Thu, 12 Jun 2025 15:55:21 +0300, Andy Shevchenko wrote:

...

> >> >     if (handle)
> >> >             err = acpi_evaluate_object(handle, "_RST", NULL, NULL);
> >> > -   else
> >> > +   else if (i2c_dev->rst)
> >> >             err = reset_control_reset(i2c_dev->rst);
> >> > +   else
> >> > +           err = tegra_i2c_master_reset(i2c_dev);
> >>
> >> Can you please take a look here? Should the reset happen in ACPI?
> >
> > This is a good question. Without seeing all the implementations of _RST method
> > for the platforms based on this SoC it's hard to say. Ideally the _RST (which
> > is called above) must handle it properly, but firmwares have bugs...
> >
> > TL;DR: I think the approach is correct, and if any bug in ACPI will be found,
> > the workaround (quirk) needs to be added here later on.
> 
> As in Thierry's comment, I was in thought of updating the code as below.
> Does it make sense or would it be better keep what it is there now?
> 
> if (handle && acpi_has_method(handle, "_RST"))
> 	err = acpi_evaluate_object(handle, "_RST", NULL, NULL);
> else if (i2c_dev->rst)
> 	err = reset_control_reset(i2c_dev->rst);
> else
> 	err = tegra_i2c_master_reset(i2c_dev);

This will change current behaviour for the ACPI based platforms that do not
have an _RST method. At bare minumum this has to be elaborated in the commit
message with an explanation why it's not a probnlem.

-- 
With Best Regards,
Andy Shevchenko