linux-kernel - Re: [RFC PATCH 0/5] PCIe EPF support for internal DMAC handling and driver update for R-Car PCIe EP to support DMAC

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Date:   Wed, 2 Mar 2022 17:17:59 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Frank Li <frank.li@....com>
Cc:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Rob Herring <robh@...nel.org>,
        linux-pci <linux-pci@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [RFC PATCH 0/5] PCIe EPF support for internal DMAC handling and
 driver update for R-Car PCIe EP to support DMAC

Hi Frank,

On Wed, Mar 2, 2022 at 3:42 PM Frank Li <frank.li@....com> wrote:
>
>
>
> > -----Original Message-----
> > From: Lad, Prabhakar <prabhakar.csengg@...il.com>
> > Sent: Thursday, February 10, 2022 3:24 AM
> > To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > Cc: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>; Kishon Vijay
> > Abraham I <kishon@...com>; Bjorn Helgaas <bhelgaas@...gle.com>; Lorenzo
> > Pieralisi <lorenzo.pieralisi@....com>; Krzysztof Wilczyński <kw@...ux.com>;
> > Arnd Bergmann <arnd@...db.de>; Greg Kroah-Hartman
> > <gregkh@...uxfoundation.org>; Marek Vasut <marek.vasut+renesas@...il.com>;
> > Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>; Rob Herring
> > <robh@...nel.org>; linux-pci <linux-pci@...r.kernel.org>; Linux-Renesas
> > <linux-renesas-soc@...r.kernel.org>; LKML <linux-kernel@...r.kernel.org>;
> > Biju Das <biju.das.jz@...renesas.com>
> > Subject: [EXT] Re: [RFC PATCH 0/5] PCIe EPF support for internal DMAC
> > handling and driver update for R-Car PCIe EP to support DMAC
>
> I use standard DMA engine API to implement Designware PCIE EP embedded DMA support.
> Please check https://lore.kernel.org/all/20220302032646.3793-3-Frank.Li@nxp.com/T/
>
Thank you for the link. The Designware PCIE EP is implemented as a DMA
engine driver so it's convenient to use the DMA engine API, whereas
the R-Car PCIe-EP is implemented as an actual PCIe EP [0].

[0] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/pci/rcar-pci-ep.yaml?h=next-20220302

Cheers,
Prabhakar


> Best regards
> Frank Li
>
> >
> > Caution: EXT Email
> >
> > Hi,
> >
> > On Thu, Feb 10, 2022 at 8:40 AM Manivannan Sadhasivam
> > <manivannan.sadhasivam@...aro.org> wrote:
> > >
> > > Hi,
> > >
> > > On Wed, Jan 26, 2022 at 07:50:38PM +0000, Lad Prabhakar wrote:
> > > > Hi All,
> > > >
> > > > The current PCIe EPF framework supports DMA data transfers using
> > external
> > > > DMA only, this patch series aims to add support for platforms
> > supporting
> > > > internal DMAC on PCIe for data transfers.
> > > >
> > > > R-Car PCIe supports internal DMAC to transfer data between Internal Bus
> > to
> > > > PCI Express and vice versa. Last patch fills up the required flags and
> > ops
> > > > to support internal DMAC.
> > > >
> > > > Patches 1-3 are for PCIe EPF core to support internal DMAC handling,
> > patch
> > > > 4/5 is to fix test cases based on the conversation [1].
> > > >
> > >
> > > This looks similar to the Synopsys eDMA IP [1] that goes with the
> > Synopsys PCIe
> > > endpoint IP. Why can't you represent it as a dmaengine driver and use the
> > > existing DMA support?
> > >
> > Let me have a look. Could you please share a link to the Synopsys PCIe
> > endpoint HW manual (the driver doesn't have a binding doc).
> >
> > Cheers,
> > Prabhakar
> >
> > > [1]
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kerne
> > l.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2Ftree%2Fdr
> > ivers%2Fdma%2Fdw-
> > edma&amp;data=04%7C01%7Cfrank.li%40nxp.com%7C95a5831aac544de2211508d9ec772f
> > 9a%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637800819106821404%7CUnknow
> > n%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI
> > 6Mn0%3D%7C3000&amp;sdata=yG39L2YBN9blGxTcXyVQwIXol8%2FCo%2FZ3GbGPIlqz6Mg%3D
> > &amp;reserved=0
> > >
> > > > Patches are based on top of [1] next branch.
> > > >
> > > > [0]
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spini
> > cs.net%2Flists%2Flinux-
> > pci%2Fmsg92385.html&amp;data=04%7C01%7Cfrank.li%40nxp.com%7C95a5831aac544de
> > 2211508d9ec772f9a%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637800819106
> > 821404%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6
> > Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=ieX2gSSHFDumc1k2iWoOfMyHg236aJTE7UZ
> > 5D74D9KM%3D&amp;reserved=0
> > > > [1]
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kerne
> > l.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fhelgaas%2Fpci.git&amp;data=04%7C
> > 01%7Cfrank.li%40nxp.com%7C95a5831aac544de2211508d9ec772f9a%7C686ea1d3bc2b4c
> > 6fa92cd99c5c301635%7C0%7C0%7C637800819106821404%7CUnknown%7CTWFpbGZsb3d8eyJ
> > WIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;
> > sdata=Qc5cW6y5OrxprDjFQ1dNMZ4ZUc656I3FZqClaUMLx%2FM%3D&amp;reserved=0
> > > >
> > > > Cheers,
> > > > Prabhakar
> > > >
> > > > Lad Prabhakar (5):
> > > >   PCI: endpoint: Add ops and flag to support internal DMAC
> > > >   PCI: endpoint: Add support to data transfer using internal dmac
> > > >   misc: pci_endpoint_test: Add driver data for Renesas RZ/G2{EHMN}
> > > >   misc: pci_endpoint_test: Add support to pass flags for buffer
> > > >     allocation
> > > >   PCI: rcar-ep: Add support for DMAC
> > > >
> > > >  drivers/misc/pci_endpoint_test.c              |  56 ++++-
> > > >  drivers/pci/controller/pcie-rcar-ep.c         | 227 ++++++++++++++++++
> > > >  drivers/pci/controller/pcie-rcar.h            |  23 ++
> > > >  drivers/pci/endpoint/functions/pci-epf-test.c | 184 ++++++++++----
> > > >  drivers/pci/endpoint/pci-epf-core.c           |  32 +++
> > > >  include/linux/pci-epc.h                       |   8 +
> > > >  include/linux/pci-epf.h                       |   7 +
> > > >  7 files changed, 483 insertions(+), 54 deletions(-)
> > > >
> > > > --
> > > > 2.25.1
> > > >