linux-kernel - Re: [PATCH v2 1/8] ohci-nxp: Driver cleanup

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Date:	Tue, 17 Apr 2012 23:03:54 +0200
From:	Roland Stigge <stigge@...com.de>
To:	Arnd Bergmann <arnd@...db.de>
CC:	arm@...nel.org, linux-arm-kernel@...ts.infradead.org,
	thierry.reding@...onic-design.de, gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-input@...r.kernel.org, dmitry.torokhov@...il.com,
	axel.lin@...il.com, broonie@...nsource.wolfsonmicro.com,
	marek.vasut@...il.com, devel@...verdev.osuosl.org,
	kevin.wells@....com, srinivas.bakki@....com
Subject: Re: [PATCH v2 1/8] ohci-nxp: Driver cleanup

Hi,

On 17/04/12 22:36, Arnd Bergmann wrote:
>> +       hcd->regs = devm_request_and_ioremap(&pdev->dev, res);
>> +       if (!hcd->regs) {
>> +               err("Failed to devm_request_and_ioremap");
>>                 ret =  -ENOMEM;
>>                 goto out4;
>>         }
>> -       hcd->regs = (void __iomem *)pdev->resource[0].start;
>> +       hcd->rsrc_start = (u64)(u32)hcd->regs;
>> +       hcd->rsrc_len = resource_size(res);
> 
> This is wrong in multiple ways:
> 
> * rsrc_start is a physical address, not an __iomem token.
> * you cannot cast a pointer to u32 in general, only to unsigned long.
> 
> The fact that you need an ugly type cast like above could have told
> you that you are doing something wrong here. I guess it should
> be
> 
> 	hcd->rsrc_start = res->start;

Right. Thanks for the hint!

Technically, I ported the bug, didn't introduce it ;-)
(pdev->resource[0].start was previously provided via resource already in
IO_ADDRESS (mapped) format). Nevertheless, it's a bug, of course, and it
didn't show up since the driver seems to not use hcd->rsrc_start anyway
(but hcd->regs).

Will post an update after making sure it's tested well.

Roland
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