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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Message-ID: <CA+V-a8tivrjPoae69pqH1D+B=_Bd7ZzKjCA0PcfBz7Rpf022mA@mail.gmail.com>
Date:   Thu, 10 Feb 2022 09:24:19 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
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: Re: [RFC PATCH 0/5] PCIe EPF support for internal DMAC handling and
 driver update for R-Car PCIe EP to support DMAC

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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/dma/dw-edma
>
> > Patches are based on top of [1] next branch.
> >
> > [0] https://www.spinics.net/lists/linux-pci/msg92385.html
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git
> >
> > 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
> >