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

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Message-ID: <20230117203215.GA144880@bhelgaas>
Date:   Tue, 17 Jan 2023 14:32:15 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Shunsuke Mie <mie@...l.co.jp>
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 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."

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.

>  .../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
>