linux-kernel - Re: [PATCH 1/4] PCI: refactor io size calculation code

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Message-ID: <BANLkTikqB2tr-jNTaqVtTpBkH5O1iYQS-Q@mail.gmail.com>
Date:	Mon, 11 Apr 2011 07:42:13 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Daniel Hellstrom <daniel@...sler.com>
Cc:	Ram Pai <linuxram@...ibm.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Clemens Ladisch <clemens@...isch.de>,
	Yinghai Lu <yinghai@...nel.org>,
	Kristoffer Glembo <kristoffer@...sler.com>
Subject: Re: [PATCH 1/4] PCI: refactor io size calculation code

On Mon, Apr 11, 2011 at 6:18 AM, Daniel Hellstrom <daniel@...sler.com> wrote:
>In commit 13583b16592a ("PCI: refactor io size calculation code"):
>>
>> refactor  code  that  calculates  the  io  size in pbus_size_io()
>> and pbus_mem_io() into separate functions.
>>
>> Signed-off-by: Ram Pai <linuxram@...xxxxxxx>
>> ---
>> drivers/pci/setup-bus.c |   66
>> ++++++++++++++++++++++++++++++-----------------
>> 1 files changed, 42 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
>> index 66cb8f4..2121215 100644
>> --- a/drivers/pci/setup-bus.c
>> +++ b/drivers/pci/setup-bus.c
>> @@ -404,6 +404,43 @@ static struct resource *find_free_bus_resource(struct
>> pci_bus *bus, unsigned lon
>>        return NULL;
>> }
>>
> ...
>
>> +
>> +static resource_size_t calculate_memsize(resource_size_t size,
>> +               resource_size_t min_size,
>> +               resource_size_t size1,
>> +               resource_size_t old_size,
>> +               resource_size_t align)
>> +{
>> +       if (size < min_size)
>> +               size = min_size;
>> +       if (old_size == 1 )
>> +               old_size = 0;
>> +       if (size < old_size)
>> +               size = old_size;
>> +       size = ALIGN(size + size1, align);
>> +       return size;
>> +}
>> +
>> /* Sizing the IO windows of the PCI-PCI bridge is trivial,
>>   since these windows have 4K granularity and the IO ranges
>>   of non-bridge PCI devices are limited to 256 bytes.
>>
>>
>
> ...
>
>> @@ -516,14 +542,6 @@ static int pbus_size_mem(struct pci_bus *bus,
>> unsigned long mask,
>>                        mem64_mask &= r->flags & IORESOURCE_MEM_64;
>>                }
>>        }
>> -       if (size < min_size)
>> -               size = min_size;
>> -       old_size = resource_size(b_res);
>> -       if (old_size == 1)
>> -               old_size = 0;
>> -       if (size < old_size)
>> -               size = old_size;
>> -
>>        align = 0;
>>        min_align = 0;
>>        for (order = 0; order <= max_order; order++) {
>> @@ -537,7 +555,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned
>> long mask,
>>                        min_align = align1 >> 1;
>>                align += aligns[order];
>>        }
>> -       size = ALIGN(size, min_align);
>> +       size = calculate_memsize(size, min_size, 0, resource_size(b_res),
>> align);
>>
>
> On my SPARC32/LEON4 PCI system I get overlapped areas, double mapped
> resources. Some BARs on PCIBUS0 are in the same non-prefetchable memory
> range as the secondary bus PCIBUS1. Changing align to min_align in the above
> call to calculate_memsize() fixes the problem, and the memory allocation is
> the same as with 2.6.36.4 kernel.
>
> I belive this is just a typo.

It does seem that way. The original code used 'min_align' and 'align'
itself is meaningless in that place.

Can you confirm that the patch you talk about as fixing things is the attached?

                  Linus

View attachment "patch.diff" of type "text/x-patch" (827 bytes)