linux-kernel - Re: [PATCH v7 2/6] pci: OF: Fix the conversion of IO ranges into IO resources.

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Message-Id: <201403141946.23921.arnd@arndb.de>
Date:	Fri, 14 Mar 2014 19:46:23 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Liviu Dudau <Liviu.Dudau@....com>
Cc:	"linux-pci" <linux-pci@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	"linaro-kernel" <linaro-kernel@...ts.linaro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>,
	Tanmay Inamdar <tinamdar@....com>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH v7 2/6] pci: OF: Fix the conversion of IO ranges into IO resources.

On Friday 14 March 2014, Liviu Dudau wrote:
> You are right, that was lazy of me. What about this version?

Yes, that seems better. Thanks for fixing it up.

But back to the more important question that I realized we have
not resolved yet:

You now have two completely independent allocation functions for
logical I/O space numbers, and they will return different numbers
for any nontrivial scenario.

> +int of_pci_range_to_resource(struct of_pci_range *range,
> +       struct device_node *np, struct resource *res)
> +{
> +       res->flags = range->flags;
> +       res->parent = res->child = res->sibling = NULL;
> +       res->name = np->full_name;
> +
> +       if (res->flags & IORESOURCE_IO) {
> +               unsigned long port = -1;
> +               int err = pci_register_io_range(range->cpu_addr, range->size);
> +               if (err)
> +                       goto invalid_range;
> +               port = pci_address_to_pio(range->cpu_addr);
> +               if (port == (unsigned long)-1) {
> +                       err = -EINVAL;
> +                       goto invalid_range;
> +               }
> +               res->start = port;
> +       } else {

This one concatenates the I/O spaces and assumes that each space starts
at bus address zero, and takes little precaution to avoid filling up IO_SPACE_LIMIT
if the sizes are too big.

>+unsigned long pci_ioremap_io(const struct resource *res, phys_addr_t phys_addr)
>+{
>+       unsigned long start, len, virt_start;
>+       int err;
>+
>+       if (res->end > IO_SPACE_LIMIT)
>+               return -EINVAL;
>+
>+       /*
>+        * try finding free space for the whole size first,
>+        * fall back to 64K if not available
>+        */
>+       len = resource_size(res);
>+       start = bitmap_find_next_zero_area(pci_iospace, IO_SPACE_PAGES,
>+                               res->start / PAGE_SIZE, len / PAGE_SIZE, 0);
>+       if (start == IO_SPACE_PAGES && len > SZ_64K) {
>+               len = SZ_64K;
>+               start = 0;
>+               start = bitmap_find_next_zero_area(pci_iospace, IO_SPACE_PAGES,
>+                                       start, len / PAGE_SIZE, 0);
>+       }
>+
>+       /* no 64K area found */
>+       if (start == IO_SPACE_PAGES)
>+               return -ENOMEM;
>+
>+       /* ioremap physical aperture to virtual aperture */
>+       virt_start = start * PAGE_SIZE + (unsigned long)PCI_IOBASE;
>+       err = ioremap_page_range(virt_start, virt_start + len,
>+                               phys_addr, __pgprot(PROT_DEVICE_nGnRE));
>+       if (err)
>+               return err;
>+
>+       bitmap_set(pci_iospace, start, len / PAGE_SIZE);
>+
>+       /* return io_offset */
>+       return start * PAGE_SIZE - res->start;
>+}

While this one will try to fall back to smaller sizes, and will honor nonzero
bus addresses.

I think we shouldn't even try to do the same thing twice, but instead just
use a single allocator. I'd prefer the one I came up with, but I realize
that I am biased here ;-)

	Arnd
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