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

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Cc: "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@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Prabhakar <prabhakar.csengg@gmail.com>,
	"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 14:10:52 +0530	[thread overview]
Message-ID: <20220210084052.GA69529@thinkpad> (raw)
In-Reply-To: <20220126195043.28376-1-prabhakar.mahadev-lad.rj@bp.renesas.com>

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?

Thanks,
Mani

[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
> 