linux-kernel - Re: [PATCH v2 2/3] i2c: pxa: prevent calling of the generic recovery init code

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 for Android: free password hash cracker in your pocket

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

Message-ID: <aJyOu_GUlDPuJXO5@smile.fi.intel.com>
Date: Wed, 13 Aug 2025 16:10:19 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Gabor Juhos <j4g8y7@...il.com>
Cc: Wolfram Sang <wsa@...nel.org>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Andi Shyti <andi.shyti@...nel.org>,
	Russell King <rmk+kernel@...linux.org.uk>,
	Andrew Lunn <andrew@...n.ch>, Hanna Hawa <hhhawa@...zon.com>,
	Robert Marko <robert.marko@...tura.hr>,
	Linus Walleij <linus.walleij@...aro.org>, linux-i2c@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Imre Kaloz <kaloz@...nwrt.org>, stable@...r.kernel.org
Subject: Re: [PATCH v2 2/3] i2c: pxa: prevent calling of the generic recovery
 init code

On Wed, Aug 13, 2025 at 12:36:45PM +0200, Gabor Juhos wrote:
> 2025. 08. 11. 22:26 keltezéssel, Andy Shevchenko írta:
> > On Mon, Aug 11, 2025 at 09:49:56PM +0200, Gabor Juhos wrote:

...

> > TBH this sounds to me like trying to hack the solution and as you pointed out
> > the problem is in pinctrl state changes. I think it may affect not only I2C case.
> 
> It is not an error in the pinctrl code. I have checked and even fixed a few bugs
> in that.
> 
> > And I didn't get how recovery code affects the initialisation (enumeration).
> 
> Without the fix, it is not possible to initiate a transaction on the bus, which
> in turn prevents enumeration.

But why? As you said below the first pin control state is changed during the
probe, which is fine, and the culprit one happens on the recovery. Why is
recovery involved in probe? This is quite confusing...

> > Do we set pin control state back and forth during probe? May be this is a root cause?
> 
> Yes, basically. The state gets changed back and forth twice. Once in driver
> probe before the controller gets initialized, then once again in
> i2c_gpio_init_generic_recovery(). The problem is caused by the second state
> change as it runs after the controller gets enabled which confuses the hardware.

...

> >>  static int i2c_pxa_init_recovery(struct pxa_i2c *i2c)
> >>  {
> >>  	struct i2c_bus_recovery_info *bri = &i2c->recovery;
> > 
> >>  		return 0;
> >>  	}
> >>  
> >> +	bri->init_recovery = i2c_pxa_init_recovery_cb;
> > 
> > This is unfortunate. I would keep the naming schema consistent, i.e. rename
> > existing function and use its original name for the new callback.
> 
> I agree, but since the change is targeted also to stable kernels, I wanted to
> keep the change as minimal as possible.

Renaming is not a big deal AFAICS, but leaving this _cb will be confusing in a
long term. I prefer name to be changed.

> >>  	bri->prepare_recovery = i2c_pxa_prepare_recovery;
> >>  	bri->unprepare_recovery = i2c_pxa_unprepare_recovery;
> >>  	bri->recover_bus = i2c_generic_scl_recovery;

-- 
With Best Regards,
Andy Shevchenko