Hi Arnd, On Thursday 25 August 2016 06:29 PM, Arnd Bergmann wrote: > On Thursday, August 18, 2016 6:44:09 PM CEST Kishon Vijay Abraham I wrote: >> Hi Arnd, >> >> On Thursday 04 August 2016 04:43 PM, Arnd Bergmann wrote: >>> On Thursday, August 4, 2016 3:32:01 PM CEST Kishon Vijay Abraham I wrote: >>>> On Wednesday 03 August 2016 07:09 PM, Joao Pinto wrote: >>>>> >>>>> 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. >>> >>> >>> What's the difference between using the EDMA on that chip or a DMA engine >>> that is part of the PCIe bridge? >> >> Do you mean the difference between using DMA on an EP (like ethernet card or >> sata card) and DMA on PCI RC system? or is it the difference between eDMA >> within the PCIe IP and system DMA? > > The latter. You write that there is no DMA in the PCIe IP, but from the > perspective of the RC, it should not matter whether the DMA engine is > part of the EP logic or behind it.
right, from the RC perspective there is no difference. What I meant is DMA support in PCIe driver has to be added newly (i.e for designware) and the the platform I have doesn't have a DMA in PCIe IP. Anyways, we'll come back to this later after I post my RFC series, maybe by this week end. Thanks Kishon
