linux-kernel - Re: [PATCH v2 4/4] selftests: pci_endpoint: Migrate to Kselftest framework

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Message-ID: <Z0nG3oAx66plv4qI@ryzen>
Date: Fri, 29 Nov 2024 14:51:26 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: kw@...ux.com, gregkh@...uxfoundation.org, arnd@...db.de,
	lpieralisi@...nel.org, shuah@...nel.org, kishon@...nel.org,
	aman1.gupta@...sung.com, p.rajanbabu@...sung.com,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	bhelgaas@...gle.com, linux-arm-msm@...r.kernel.org, robh@...nel.org,
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v2 4/4] selftests: pci_endpoint: Migrate to Kselftest
 framework

Hello Mani,

On Fri, Nov 29, 2024 at 02:54:15PM +0530, Manivannan Sadhasivam wrote:
> Migrate the PCI endpoint test to Kselftest framework. All the tests that
> were part of the previous pcitest.sh file were migrated.
> 
> Below is the exclusive list of tests:
> 
> 1. BAR Tests (BAR0 to BAR5)
> 2. Legacy IRQ Tests
> 3. MSI Interrupt Tests (MSI1 to MSI32)
> 4. MSI-X Interrupt Tests (MSI-X1 to MSI-X2048)
> 5. Read Tests - MEMCPY (For 1, 1024, 1025, 1024000, 1024001 Bytes)
> 6. Write Tests - MEMCPY (For 1, 1024, 1025, 1024000, 1024001 Bytes)
> 7. Copy Tests - MEMCPY (For 1, 1024, 1025, 1024000, 1024001 Bytes)
> 8. Read Tests - DMA (For 1, 1024, 1025, 1024000, 1024001 Bytes)
> 9. Write Tests - DMA (For 1, 1024, 1025, 1024000, 1024001 Bytes)
> 10. Copy Tests - DMA (For 1, 1024, 1025, 1024000, 1024001 Bytes)

I'm not sure if it is a great idea to add test case number 10.

While it will work if you use the "dummy memcpy" DMA channel which uses
MMIO under the hood, if you actually enable a real DMA controller (which
often sets the DMA_PRIVATE cap in the DMA controller driver (e.g. if you
are using a DWC based PCIe EP controller and select CONFIG_DW_EDMA=y)),
pci_epf_test_copy() will fail with:
[   93.779444] pci_epf_test pci_epf_test.0: Cannot transfer data using DMA

See:
https://github.com/torvalds/linux/blob/v6.12/drivers/pci/endpoint/functions/pci-epf-test.c#L363-L368


Kind regards,
Niklas