Oh, I right after I sent my previous email, I realized how it's working. The endpoint test driver (drivers/pci/endpoint/functions/pci-epf-test.c) queues delayed work after linkup or binding (binding epc and epf), or after processing the delayed work (re-queues). And in the delayed work performs the function "pci_epf_test_cmd_handler" and there it reads the command register and performs various actions including DMA read for the 'write test from the RC' that I mentioned in my previous email. After it performs the command, it sends interrupt to the host using rais_irq function. I had analyzed this pci-epf-test.c before and right after sending my question I realized how it's working after searching 'raise_irq' in the endpoint test code. Thank you. Best regards, Chan Kim >-----Original Message----- >From: Chan Kim <ckim@xxxxxxxxxx> >Sent: Thursday, September 14, 2023 2:39 PM >To: kernelnewbies@xxxxxxxxxxxxxxxxx >Subject: A question on endpoint_test code in the linux source by Kishon >Vijay Abraham I. > >Hello linux experts, > >I was analyzing drivers/misc/pci_endpoint_test.c (linux-5.15.68) It uses a >miscdev and when the driver receives PCITEST_WRITE command using ioctl(line >726 in the link below) from the user, the driver sets registers of the >endpoint device and writes COMMAND_READ at register >PCI_ENDPOINT_TEST_COMMAND >(https://elixir.bootlin.com/linux/v5.15.68/source/drivers/misc/pci_endpoin >t_ >test.c#L553 ). This seems to be setting DMA paramaters (source DMA address >and size) and triggering DMA. The driver then waits for completion and I can >see the interrupt service routine completes the completion(test->irq_raised). >I guess the endpoint device should actually do the DMA-read (when told to >use DMA) or read the data to itself(I don't know where it is) and send >interrupt to the host(using msix or msi or intx). > >The code was written by "Kishon Vijay Abraham I" and I know it is supposed >to be run with drivers/pci/endpoint/functions/pci-epf-test.c >(https://elixir.bootlin.com/linux/v5.15.68/source/drivers/pci/endpoint/fun >ct >ions/pci-epf-test.c) in the endpoint side. And how to use this endpoint >framework test is shown in https://docs.kernel.org/PCI/endpoint/pci-test- >howto.html . But I cannot find where the actual DMA and sending interrupt is >occurring in the endpoint side source code when the registers at set. Am I >supposed to be running this code with some real hardware?(as listed in the >pci_device_id in the hostside pci_endpoint_test.c driver?) Where can I find >the corresponding (acting on the register triggering above) action in the >endpoint side? > >If you have once seen these codes and send me any hint or suggestion, I'll >be grateful. >Thank you. > >Best regards, >Chan Kim > > > > > >_______________________________________________ >Kernelnewbies mailing list >Kernelnewbies@xxxxxxxxxxxxxxxxx >https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
