linux-kernel - Re: [PATCH v2 1/3] PCI: endpoint: Handle 64-bit BARs properly

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Date:   Fri, 9 Feb 2018 18:14:49 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     Niklas Cassel <niklas.cassel@...s.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Sekhar Nori <nsekhar@...com>,
        Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>,
        Niklas Cassel <niklass@...s.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        John Keeping <john@...anate.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] PCI: endpoint: Handle 64-bit BARs properly

Hi Bjorn,

On Friday 09 February 2018 03:27 AM, Bjorn Helgaas wrote:
> On Thu, Feb 08, 2018 at 06:17:32PM +0530, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On Thursday 08 February 2018 06:03 PM, Niklas Cassel wrote:
>>> A 64-bit BAR uses the succeeding BAR for the upper bits, therefore
>>> we cannot call pci_epc_set_bar() on a BAR that follows a 64-bit BAR.
>>>
>>> If pci_epc_set_bar() is called with flag PCI_BASE_ADDRESS_MEM_TYPE_64,
>>
>> Not related to $patch. But I have a query on when
>> PCI_BASE_ADDRESS_MEM_TYPE_64 should be set. Whether if the size is >
>> 4G or if the address can be mapped anywhere in the 64-bit PCIe
>> address space or both?
> 
> In general, PCI_BASE_ADDRESS_MEM_TYPE_64 should be set if the BAR is
> 64 bits wide.  IORESOURCE_MEM_64 is similar.

okay, if the HW support 64bit BAR, 64 bit flag should be set and not based on
size or anything else?

Thanks
Kishon