linux-kernel - Re: [RFC PATCH 0/3] Deal with alignment restriction on EP side

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Message-ID: <1b26c1e2-62e5-920f-f480-b66b1f903e65@igel.co.jp>
Date:   Wed, 18 Jan 2023 19:17:21 +0900
From:   Shunsuke Mie <mie@...l.co.jp>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
        Hou Zhiqiang <Zhiqiang.Hou@....com>,
        Frank Li <Frank.Li@....com>, Li Chen <lchen@...arella.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/3] Deal with alignment restriction on EP side


On 2023/01/18 5:32, Bjorn Helgaas wrote:
> On Fri, Jan 13, 2023 at 06:03:47PM +0900, Shunsuke Mie wrote:
>> Some PCIe EPC controllers have restriction to map PCIe address space to the
>> local memory space. The mapping is needed to access memory of other side.
>> On epf test, RC module prepares an aligned memory, and EP module maps the
>> region. However, a EP module which emulate a device (e.g. VirtIO, NVMe and
>> etc) cannot expect that a driver for the device prepares an aligned memory.
>> So, a EP side should deal with the alignment restriction.
>>
>> This patchset addresses with the alignment restriction on EP size. A
>> content as follows:
>> 1. Improve a pci epc unmap/map functions to cover the alignment restriction
>> with adding epc driver support as EPC ops.
>> 2. Implement the support function for DWC EPC driver.
>> 3. Adapt the pci-epf-test to the map/unmap function updated at first patch.
>>
>> I tested this changes on RENESAS board has DWC PCIeC.
>>
>> This is a RFC, and it has patches for testing only. Following changes are
>> not included yet:
>> 1. Removing alignment codes on RC side completely
>> 2. Adapting map/unmap() changes to pci-epf-ntb/vntb
>>
>> Best,
>> Shunsuke
>>
>> Shunsuke Mie (3):
>>    PCI: endpoint: support an alignment aware map/unmaping
>>    PCI: dwc: support align_mem() callback for pci_epc_epc
>>    PCI: endpoint: support pci_epc_mem_map/unmap API changes
> s/unmaping/unmapping/
>
> Capitalize subject lines ("Support ...").
>
> Would be nice to say something more specific than "support ... API
> changes."
I'll reflect this remarks.
>
> The last patch seems to be for a test case.  Some previous changes to
> it use the "PCI: pci-epf-test" prefix so it's distinct from the
> pci-epc-core changes.
I'll follow the previous changes.
>>   .../pci/controller/dwc/pcie-designware-ep.c   | 13 +++
>>   drivers/pci/endpoint/functions/pci-epf-test.c | 89 +++++--------------
>>   drivers/pci/endpoint/pci-epc-core.c           | 57 +++++++++---
>>   include/linux/pci-epc.h                       | 10 ++-
>>   4 files changed, 90 insertions(+), 79 deletions(-)
>>
>> -- 
>> 2.25.1
>>
Best,

Shunsuke