From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: "Lad Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>,
"Kishon Vijay Abraham I" <kishon@ti.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Marek Vasut" <marek.vasut+renesas@gmail.com>,
"Yoshihiro Shimoda" <yoshihiro.shimoda.uh@renesas.com>,
"Rob Herring" <robh@kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"Biju Das" <biju.das.jz@bp.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
Date: Thu, 10 Feb 2022 11:05:45 +0000 [thread overview]
Message-ID: <CA+V-a8tfUgvzPyMe_FHuz=8mmC6dPHP7E=e+nCzOey04vCcAkg@mail.gmail.com> (raw)
In-Reply-To: <20220210105023.GB69529@thinkpad>
On Thu, Feb 10, 2022 at 10:50 AM Manivannan Sadhasivam
<manivannan.sadhasivam@linaro.org> wrote:
>
> On Thu, Feb 10, 2022 at 09:24:19AM +0000, Lad, Prabhakar wrote:
> > Hi,
> >
> > On Thu, Feb 10, 2022 at 8:40 AM Manivannan Sadhasivam
> > <manivannan.sadhasivam@linaro.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).
> >
>
> I don't think the PCIe reference manual is available publicly. And you are right
> that the driver is not tied to devicetree. The reason is, it gets probed using
> the PCI ID of the EP and all the resources are defined statically in the driver
> itself.
>
In R-Car PCIe the internal dmac is part of the PCIe block itself [0]
and not a separate block. I don't see any drivers implementing the
internal dmac drivers as a DMA engine driver. For example the Renesas
SDHI driver has internal dmac too, this is handled in the SDHI driver
itself [1] and not implemented as DMA engine driver. Let me know if my
understanding is wrong here.
[0] https://elixir.bootlin.com/linux/v5.17-rc3/source/Documentation/devicetree/bindings/pci/rcar-pci-ep.yaml#L76
[1] https://elixir.bootlin.com/linux/v5.17-rc3/source/drivers/mmc/host/renesas_sdhi_internal_dmac.c
Cheers,
Prabhakar
> Thanks,
> Mani
>
> > 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
> > > >
next prev parent reply other threads:[~2022-02-10 11:06 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 19:50 [RFC PATCH 0/5] PCIe EPF support for internal DMAC handling and driver update for R-Car PCIe EP to support DMAC Lad Prabhakar
2022-01-26 19:50 ` [RFC PATCH 1/5] PCI: endpoint: Add ops and flag to support internal DMAC Lad Prabhakar
2022-02-14 9:30 ` Manivannan Sadhasivam
2022-01-26 19:50 ` [RFC PATCH 2/5] PCI: endpoint: Add support to data transfer using internal dmac Lad Prabhakar
2022-02-14 9:49 ` Manivannan Sadhasivam
2022-01-26 19:50 ` [RFC PATCH 3/5] misc: pci_endpoint_test: Add driver data for Renesas RZ/G2{EHMN} Lad Prabhakar
2022-02-14 10:02 ` Manivannan Sadhasivam
2022-01-26 19:50 ` [RFC PATCH 4/5] misc: pci_endpoint_test: Add support to pass flags for buffer allocation Lad Prabhakar
2022-02-14 10:11 ` Manivannan Sadhasivam
2022-01-26 19:50 ` [RFC PATCH 5/5] PCI: rcar-ep: Add support for DMAC Lad Prabhakar
2022-02-14 10:40 ` Manivannan Sadhasivam
2022-02-21 4:32 ` [EXT] " Li Chen
2022-02-09 4:47 ` [EXT] [RFC PATCH 0/5] PCIe EPF support for internal DMAC handling and driver update for R-Car PCIe EP to support DMAC Li Chen
2022-02-09 8:52 ` Lad, Prabhakar
2022-02-10 5:54 ` Li Chen
2022-02-10 7:47 ` Greg Kroah-Hartman
2022-02-10 8:40 ` Manivannan Sadhasivam
2022-02-10 9:24 ` Lad, Prabhakar
2022-02-10 10:50 ` Manivannan Sadhasivam
2022-02-10 11:05 ` Lad, Prabhakar [this message]
2022-02-10 13:22 ` Manivannan Sadhasivam
2022-03-02 15:42 Frank Li
2022-03-02 17:17 ` Lad, Prabhakar
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