> -----Original Message----- > From: Kishon Vijay Abraham I [mailto:[email protected]] > Sent: Thursday, August 04, 2016 6:02 PM > To: Joao Pinto <[email protected]>; [email protected]; linux- > [email protected]; [email protected]; Jingoo Han <[email protected]>; > Pratyush Anand <[email protected]> > Cc: Ley Foon Tan <[email protected]>; Rob Herring <[email protected]>; > Tanmay Inamdar <[email protected]>; Roy Zang <tie- > [email protected]>; Mingkai Hu <[email protected]>; > Minghuan Lian <[email protected]>; Richard Zhu > <[email protected]>; Lucas Stach <[email protected]>; > Murali Karicheri <[email protected]>; Thomas Petazzoni > <[email protected]>; Jason Cooper > <[email protected]>; Thierry Reding <[email protected]>; > Simon Horman <[email protected]>; Zhou Wang > <[email protected]>; Gabriele Paoloni > <[email protected]>; Stanimir Varbanov <svarbanov@mm- > sol.com>; David Daney <[email protected]>; linux- > [email protected]; [email protected]; linux- > [email protected]; Carlos Palminha > <[email protected]> > Subject: Re: Support for configurable PCIe endpoint > > Hi, > > On Wednesday 03 August 2016 07:09 PM, Joao Pinto wrote: > > Hi Kishon, > > > > On 8/3/2016 7:03 AM, Kishon Vijay Abraham I wrote: > >> Hi, > >> > >> The PCIe controller present in TI's DRA7 SoC is capable of operating > >> either in Root Complex mode or Endpoint mode. (It uses Synopsys > >> Designware Core). I'd assume most of the PCIe controllers on other > >> platforms that use Designware core should also be capable to operate > >> in endpoint mode. But linux kernel right now supports only RC mode. > >> > >> PCIe endpoint support discussion came up briefly before [1] but it > >> was felt the practical use case will find firmware more suitable and > >> endpoint support in kernel can be used only for validation or demo. > >> > >> *) Modify platform driver to support EP mode (in my case pci-dra7xx.c). > >> > >> *) dt binding specific to EP mode should be created. > >> > >> Once I complete the implementation and start posting RFC patches, a > >> lot of these will become clear. But I want to check if this sounds > >> okay to you guys before starting the implementation. > >> > >> Let me know if you have some other ideas too. > >> > >> Cheers > >> Kishon > >> > >> [1] -> http://www.spinics.net/lists/linux-pci/msg26026.html > >> > > > > You are rising a topic that we are also addressing in Synopsys. > > > > For the PCIe RC hardware validation we are currently using the > > standard pcie-designware and pcie-designware-plat drivers. > > > > For the Endpoint we have to use an internal software package. Its main > > purpose is to initialize the IP registers, eDMA channels and make data > > transfer to prove that the everything is working properly. This is > > done in 2 levels, a custom driver built and loaded and an application > > that makes some ioctl to the driver executing some interesting > > functions to check the Endpoint status and make some data exchange. > > hmm.. the platform I have doesn't have a DMA in PCIe IP > (http://www.ti.com/lit/ug/spruhz6g/spruhz6g.pdf). So in your testing does > the EP access RC memory? i.e the driver in the RC allocates memory from it's > DDR and gives it's DDR address to the EP. The EP then transfers data to this > address. (This is a typical use case with ethernet PCIe cards). IIUC that's > not > simple with configurable EPs. I'd like to know more about your testing though. >
Hi Kishon, This is a typical user case for EP to use DMA transfer data to/from RC memory. In our case, we implement ring (like BD ring) or register in EP to communicate The address allocated in RC memory, then EP can transfer data to/from RC memory. Thanks, Mingkai
