Messages in this thread Patch in this message | | | Date | Mon, 29 Sep 2008 11:10:49 -0600 | From | Grant Grundler <> | Subject | Re: [PATCH] pci: introduce users of ioremap_pcibar() |
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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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