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    SubjectRe: [PATCH] pci: introduce users of ioremap_pcibar()
    On Mon, Sep 29, 2008 at 06:42:20AM -0700, Arjan van de Ven wrote:
    ...
    > > This patch changes that behavior of the device driver so it uses
    > > uncacheable instead of cacheable mappings. This is the only thing
    > > I'm uncertain about for this patch.
    >
    > ioremap() also is uncachable today.

    Ok...it was using cacheable mapping on ia64 until this commit in 2007:
    http://www.gelato.unsw.edu.au/archives/linux-ia64/0703/20211.html

    I stopped paying close attention on ia64 in 2006 for the most part.
    It's always been uncacheable on parisc.

    After finding willy's patch (March 2006) on lwn.net, I remember the
    discussion around changing the behavior of ioremap() to be uncached:
    http://lwn.net/Articles/178084/

    And I have to agree with willy/alan, pci_iomap() is already doing this.

    However, pci_iomap() isn't quite right either:
    if (flags & IORESOURCE_MEM) {
    if (flags & IORESOURCE_CACHEABLE)
    return ioremap(start, len);
    return ioremap_nocache(start, len);
    }

    I expect it needs to use ioremap_cache() instead of ioremap().
    One line patch below fixes that. Build-tested on x86 only.

    Signed-off-by: Grant Grundler <grundler@parisc-linux.org>

    > > And I have a second issue less important issue.
    > > What is the result of ioremap_pcibar(pci, 1) when BAR0 is a 64-bit
    > > bar? Given the name, I expect to call "ioremap_pcibar(pci,2)" to get
    > > the desired result. Maybe just document how to handle this correctly
    > > in Documentation/pci.txt would be sufficient.
    >
    > we should detect this and DTRT inside the implementation, not in the
    > drivers.

    pci_iomap() is already doing this. See lib/iomap.c:pci_iomap().

    thanks,
    grant


    diff --git a/lib/iomap.c b/lib/iomap.c
    index d322293..5565cf9 100644
    --- a/lib/iomap.c
    +++ b/lib/iomap.c
    @@ -267,7 +267,7 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen)
    return ioport_map(start, len);
    if (flags & IORESOURCE_MEM) {
    if (flags & IORESOURCE_CACHEABLE)
    - return ioremap(start, len);
    + return ioremap_cache(start, len);
    return ioremap_nocache(start, len);
    }
    /* What? */

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