Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for IO

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for IO
Date	2015-10-12 11:20 +0200
Message-ID	<qiHqV-2Xd-5@gated-at.bofh.it> (permalink)
References	<qhGQk-4IM-43@gated-at.bofh.it> <qiuk1-L5-3@gated-at.bofh.it> <qiGuR-1Ag-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, 12 Oct 2015, Andy Shevchenko wrote:
> On Sun, 2015-10-11 at 21:18 +0200, Thomas Gleixner wrote:
> > Andy,
> > 
> > On Fri, 9 Oct 2015, Andy Shevchenko wrote:
> > >  #ifdef CONFIG_PCI
> > >  static void mem32_serial_out(unsigned long addr, int offset, int 
> > value)
> > >  {
> > > -     u32 *vaddr = (u32 *)addr;
> > > +     void __iomem *vaddr = (void __iomem *)addr;
> > >       /* shift implied by pointer type */
> > >       writel(value, vaddr + offset);
> > 
> > This is broken. Assume vaddr = 0x1000 and offset = 1
> 
> Yes, I noticed in reply to myself  
> http://www.spinics.net/lists/kernel/msg2094143.html
> 
> Tests were okay because platform I have is using 8-bit I/O.
> 
> Does it make sense to use the following approach?
> 
>  void __iomem *vaddr = (void __iomem *)addr;
>  writel(value, vaddr + offset << 2);

What's wrong with: u32 __iomem *vaddr ?

Thanks,

	tglx


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[PATCH v2 1/1] x86/early_printk: Use __iomem address space for IO Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2015-10-09 16:30 +0200
  Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for  IO Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2015-10-09 16:40 +0200
  Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for  IO Thomas Gleixner <tglx@linutronix.de> - 2015-10-11 21:20 +0200
    Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for  IO Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2015-10-12 10:20 +0200
      Re: [PATCH v2 1/1] x86/early_printk: Use __iomem address space for  IO Thomas Gleixner <tglx@linutronix.de> - 2015-10-12 11:20 +0200

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