Re: [PATCH] PCI: endpoint: pci-epf-test: Move DMA check into read/write/copy functions

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Aug 06, 2024 at 06:27:54PM +0200, Rick Wertenbroek wrote:
> The test for a DMA transfer was done in pci_epf_test_cmd_handler, which
> if not supported would lead to the endpoint function just printing an
> error message and waiting for further commands. This would leave the

I guess it's the *test* that prints the error message?  Is this the
"Cannot transfer data using DMA" message?

> host side PCI driver waiting for an interrupt because the call to
> pci_epf_test_raise_irq is skipped. The host side driver
> drivers/misc/pci_endpoint_test.c would hang indefinitely when sending
> a transfer request with DMA if the endpoint does not support it.
> This is because wait_for_completion() is used in the host side driver.
> 
> Move the DMA check into the read/write/copy functions so that they
> report a transfer (IO) error so that pci_epf_test_raise_irq() is
> called when a transfer with DMA is requested, even if unsupported.

Add "()" after function names above, as you did for
pci_epf_test_raise_irq().

> The host side driver will still report an error on transfer thanks
> to the checksum, because no data was moved, but will not hang anymore
> waiting for an interrupt that will never arrive.