On Mon, Apr 24, 2017 at 11:52:27AM +0530, abhijit wrote: > Hi Lorenzo, > > Yes that's true.. > > My question is: what if EP function default completer ID means BDF > has values = 0(meaning B = 0, D = 0, f = 0) and Root complex > requester ID also has same BDF, that is 0. > > Is that valid case as per PCIe standard, as in this case, requester > ID and completion ID have same BDF? Read "2.2.9: Completion rules" and you will have your question answered there ;-) Lorenzo > > Thank you very much for your replies > > Regards, > Abhijit > > > On Friday 21 April 2017 09:29 PM, Lorenzo Pieralisi wrote: > >On Fri, Apr 21, 2017 at 03:33:45PM +0530, abhijit naik wrote: > >> Hi Lorenzo, > >> Thank you very much for reply. > >> As you mentioned I noted that, "If a Function must generate a Completion > >> prior to the initial device Configuration Write Request, 0's must be > >> entered into the Bus Number and Device Number fields" > >> By above statement this means that completion ID will be 0x0000. For the > >> first device on any bus, device number will be 0 and function number will > >> be 0. > >> Isn't completer (for configuration read) packet will be addressing itself > >> instead of root complex with bus, device and function number 0? > > > >I don't understand what you are asking. The completion (containing > >the read data) is routed back to the initiator via ID (of the requester) > >routing. > > > >2.2.4.2 > >2.2.9 > > > >Lorenzo > > > >> On Wed, Apr 19, 2017 at 3:56 PM, Lorenzo Pieralisi > >> <lorenzo.pieralisi@xxxxxxx> wrote: > >> > >> On Tue, Apr 11, 2017 at 07:45:40PM +0530, abhijit wrote: > >> > > >> > Hi All, > >> > > >> > I was referring Linux code for PCIe enumeration and I have one doubt > >> > w.r.t to very first operation that must be done on device. > >> > > >> > Currently while scanning for device, we directly read vendor ID from > >> > device. But PCIE base specification > >> > "CB-PCI_Express_Base_4.0r0.7_November-11-2016.pdf" section 2.2.6.2 > >> > specifies that, > >> > > >> > "Functions must capture the Bus and Device Numbers supplied with all > >> > Type 0 Configuration Write Requests completed by the Function and > >> > supply these numbers in the Bus and Device Number fields of the > >> > Requester ID for all Requests initiated by the Device/Function." > >> > >> Please note: > >> "for all Requests initiated by the Device/Function". > >> ^^^^^^^^^ > >> > Here I am assuming, the completer ID will be device number and > >> > function number that will eventually programmed in to device. In > >> > that case, my question is, without first write, how read > >> > request(VENDOR ID read) is serviced/routed? > >> > >> That's not initiated by the endpoint device, it is routed by > >> requester ID, which is the requester ID of the configuration > >> request - ie master (ie root complex) requester ID. > >> > >> Read 2.2.9 - Completion rules > >> > >> HTH, > >> Lorenzo > >> > >> -- > >> Best wishes, > >> Abhijit Naik
