Subject: Re: [PATCH] powerpc/5200: Bugfix for PCI mapping of memory and IMMR

From: Andre Schwarz <[email-masked]>
Date: Fri, 30 Jan 2009 09:33:03 +0100

Matt Sealey wrote:
> On Mon, Jan 26, 2009 at 10:34 PM, Grant Likely
> <[email-masked]> wrote:
>   
>> From: Grant Likely <[email-masked]>
>>
>> This patch ensures that memory gets properly mapped into the PCI
>> address space.  Without this patch, the memory window BAR is left
>> at whatever value happened to be loaded into the BAR when Linux
>> was booted.  Without this patch, memory could end up getting mapped
>> at any of the 1G address boundaries instead of at '0' where Linux
>> expects it.
>>
>> Similarly, this patch also ensures that the internally memory mapped
>> registers (IMMR) are mapped to the correct PCI address range.
>>
>> Without this patch, PCI appears to work correctly until a PCI
>> device is inserted which DMAs into memory.
>>
>> Signed-off-by: Grant Likely <[email-masked]>
>> ---
>>
>> This is a bugfix that I intend to merge into 2.6.29 and once it is
>> mainlined get it added to the stable queue.  If you have a 5200 system,
>> please test and make sure it works for you.
>>
>> Thanks
>> g.
>>
>>  arch/powerpc/platforms/52xx/mpc52xx_pci.c |   24 ++++++++++--------------
>>  1 files changed, 10 insertions(+), 14 deletions(-)
>>
>>     
>
> This doesn't affect Efika, right?
>
> What's the expected impact and how come nobody tried a DMA-capable PCI
> card in an MPC5200B board before? :)
>
>   
We're running a MPC5200B based board with an external FPGA pumping as 
much data into the CPU's memory as possible using scatter-gather DMA. No 
problems so far ... besides the lousy PCI target performance of the 
5200, of course. Of course we've been always running latest u-boot.

regards,
Andre

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