Re: [EXT] 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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Hi Kishon,

On Wed, Mar 2, 2022 at 6:28 PM Frank Li <frank.li@xxxxxxx> wrote:
>
>
>
> > -----Original Message-----
> > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > Sent: Wednesday, March 2, 2022 11:18 AM
> > To: Frank Li <frank.li@xxxxxxx>
> > Cc: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>; Lad Prabhakar
> > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>; Kishon Vijay Abraham I
> > <kishon@xxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Lorenzo Pieralisi
> > <lorenzo.pieralisi@xxxxxxx>; Krzysztof Wilczyński <kw@xxxxxxxxx>; Arnd
> > Bergmann <arnd@xxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>;
> > Marek Vasut <marek.vasut+renesas@xxxxxxxxx>; Yoshihiro Shimoda
> > <yoshihiro.shimoda.uh@xxxxxxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; linux-
> > pci <linux-pci@xxxxxxxxxxxxxxx>; Linux-Renesas <linux-renesas-
> > soc@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; Biju Das
> > <biju.das.jz@xxxxxxxxxxxxxx>
> > 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
> >
> > Caution: EXT Email
> >
> > Hi Frank,
> >
> > On Wed, Mar 2, 2022 at 3:42 PM Frank Li <frank.li@xxxxxxx> wrote:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > > Sent: Thursday, February 10, 2022 3:24 AM
> > > > To: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > > > Cc: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>; Kishon
> > Vijay
> > > > Abraham I <kishon@xxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Lorenzo
> > > > Pieralisi <lorenzo.pieralisi@xxxxxxx>; Krzysztof Wilczyński
> > <kw@xxxxxxxxx>;
> > > > Arnd Bergmann <arnd@xxxxxxxx>; Greg Kroah-Hartman
> > > > <gregkh@xxxxxxxxxxxxxxxxxxx>; Marek Vasut
> > <marek.vasut+renesas@xxxxxxxxx>;
> > > > Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>; Rob Herring
> > > > <robh@xxxxxxxxxx>; linux-pci <linux-pci@xxxxxxxxxxxxxxx>; Linux-Renesas
> > > > <linux-renesas-soc@xxxxxxxxxxxxxxx>; LKML <linux-
> > kernel@xxxxxxxxxxxxxxx>;
> > > > Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > > 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kern
> > el.org%2Fall%2F20220302032646.3793-3-
> > Frank.Li%40nxp.com%2FT%2F&amp;data=04%7C01%7Cfrank.li%40nxp.com%7C0e2e5fe8f
> > d224076afb208d9fc70aa16%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637818
> > 383096028914%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLC
> > JBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=DCDX%2BYEVFsPOE6ZWzwrMxk1Fjlk
> > ZA%2FEPGmhQSHuPB2c%3D&amp;reserved=0
> > >
> > 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].
>
> My means, needn't add new interface pci_epf_internal_dmac_xfr at epc/epf.
> Your R-Car PCI-EP DMA part can implement as a dma engine driver like designware.
>
> So EP functional driver use the same method to operate DMA regardless
> EP controller type.
>
With this approach all the PCIe controllers supporting internal dmac
will have to be added as a DMA driver.

Could you please provide some feedback on the above?

Sorry this mail is not in chain to my orignal patch series. My orignal
series can be found at [0]

[0] https://patchwork.kernel.org/project/linux-renesas-soc/cover/20220126195043.28376-1-prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx/

Cheers,
Prabhakar




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