linux-kernel - Re: [PATCH v2] pinctrl/nomadik: make independent of prcmu driver

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Date:	Sun, 11 Nov 2012 19:40:43 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Stephen Warren <swarren@...dotorg.org>,
	Jean Nicolas Graux <jean-nicolas.graux@...ricsson.com>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Anmar Oueja <anmar.oueja@...aro.org>,
	Stephen Warren <swarren@...dia.com>,
	Loic Pallardy <loic.pallardy@...com>,
	Jonas Aaberg <jonas.aberg@...ricsson.com>
Subject: Re: [PATCH v2] pinctrl/nomadik: make independent of prcmu driver

On Fri, Nov 9, 2012 at 6:16 PM, Stephen Warren <swarren@...dotorg.org> wrote:

> [Me]
>> +     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     if (res) {
>> +             npct->prcm_base = devm_ioremap(&pdev->dev, res->start,
>> +                                            resource_size(res));
>> +             if (!npct->prcm_base) {
>> +                     dev_err(&pdev->dev,
>> +                             "failed to ioremap PRCM registers\n");
>> +                     return -ENOMEM;
>> +             }
>> +     } else {
>> +             dev_info(&pdev->dev,
>> +                      "No PRCM base, assume no ALT-Cx control is available\n");
>> +     }
>
> Where is "assume no ALT-Cx control is available" implemented; I don't
> see anything that uses npct->prcm_base to conditionally enable/block any
> features. Is it just assumed that the DT won't contain any entries that
> trigger writes to the PRCM registers? That seems fragile; it could cause
> a "user"-triggered kernel crash.

Yeah. That's been in for a while, so this patch in itself is not making
things more fragile, it came with the first Alt-Cx patch.
So it is indeed based on good faith in the maps.

I'm poking Jean-Nicolas to have a look at hardening
this with some check, ping!

> Aside from that, this seems fine. Much smaller than V1:-)

Yeah, thanks for poking us...

Yours,
Linus Walleij
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