Re: [PATCH 2/3] PCI: rcar: Allow 64bit MSI addresses

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On 3/17/19 10:12 AM, Wolfram Sang wrote:
> On Sun, Mar 17, 2019 at 01:06:07AM +0100, marek.vasut@xxxxxxxxx wrote:
>> From: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
>>
>> The MSI address can be 64bit. Switch the data type used to hold the
>> result of virt_to_phys() to phys_addr_t to reflect it's properties
>> correctly and program the top 32bits of PA into PCIEMSIAUR.
>>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
> 
> Looks sane. Not being a PCI expert, I wonder: Were we just lucky to not
> hit a 64-bit MSI address before?

I wonder about that, virt_to_phys(__get_free_pages(GFP_KERNEL, 0)) would
happily return 64bit address, but with the cards I tested (a few intel
NICs [igb, e1000e], PCIe NVME SSDs and xHCI HCD), I am getting the MSIs
either way.

> Is this tied to our 32-bit limitation?

This might be a question for the HW team. I would be tempted to
cautiously say yes.

-- 
Best regards,
Marek Vasut



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