The pci-epf-test PCI endpoint function /drivers/pci/endpoint/function/pci-epf_test.c is meant to be used in a PCI endpoint device connected to a host computer with the host side driver: /drivers/misc/pci_endpoint_test.c. The host side driver can request read/write/copy transactions from the endpoint function and expects an IRQ from the endpoint function once the read/write/copy transaction is finished. These can be issued with or without DMA enabled. If the host side driver requests a read/write/copy transaction with DMA enabled and the endpoint function does not support DMA, the endpoint would only print an error message and wait for further commands without sending an IRQ because pci_epf_test_raise_irq() is skipped in pci_epf_test_cmd_handler(). This results in the host side driver hanging indefinitely waiting for the IRQ. Call pci_epf_test_raise_irq() when a transfer with DMA is requested but DMA is unsupported. The host side driver will no longer hang but report an error on transfer (printing "NOT OKAY") thanks to the checksum because no data was moved. Clarify the error message in the endpoint function as "Cannot ..." is vague and does not state the reason why it cannot be done. Signed-off-by: Rick Wertenbroek <rick.wertenbroek@xxxxxxxxx> --- drivers/pci/endpoint/functions/pci-epf-test.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c index 7c2ed6eae53a..b02193cef06e 100644 --- a/drivers/pci/endpoint/functions/pci-epf-test.c +++ b/drivers/pci/endpoint/functions/pci-epf-test.c @@ -649,7 +649,8 @@ static void pci_epf_test_cmd_handler(struct work_struct *work) if ((READ_ONCE(reg->flags) & FLAG_USE_DMA) && !epf_test->dma_supported) { - dev_err(dev, "Cannot transfer data using DMA\n"); + dev_err(dev, "DMA transfer not supported\n"); + pci_epf_test_raise_irq(epf_test, reg); goto reset_handler; } -- 2.25.1