linux-kernel - Re: [PATCH v4 0/5] PCI: EP: Add RC-to-EP doorbell with platform MSI controller

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Message-ID: <Zys4qs-uHvISaaPB@ryzen>
Date: Wed, 6 Nov 2024 10:36:42 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	imx@...ts.linux.dev, dlemoal@...nel.org, maz@...nel.org,
	tglx@...utronix.de, jdmason@...zu.us
Subject: Re: [PATCH v4 0/5] PCI: EP: Add RC-to-EP doorbell with platform MSI
 controller

On Wed, Nov 06, 2024 at 10:15:27AM +0100, Niklas Cassel wrote:
> 
> I do get a domain, but I do not get any IRQ on the EP side when the RC side is
> writing the doorbell (as part of pcitest -B),
> 
> [    7.978984] pci_epc_alloc_doorbell: num_db: 1
> [    7.979545] pci_epf_test_bind: doorbell_addr: 0x40
> [    7.979978] pci_epf_test_bind: doorbell_data: 0x0
> [    7.980397] pci_epf_test_bind: doorbell_bar: 0x1
> [   21.114613] pci_epf_enable_doorbell db_bar: 1
> [   21.115001] pci_epf_enable_doorbell: doorbell_addr: 0xfe650040
> [   21.115512] pci_epf_enable_doorbell: phys_addr: 0xfe650000
> [   21.115994] pci_epf_enable_doorbell: success
> 
> # cat /proc/interrupts | grep epc
> 117:          0          0          0          0          0          0          0          0  ITS-pMSI-a40000000.pcie-ep   0 Edge      pci-epc-doorbell0
> 
> Even if I try to write the doorbell manually from EP side using devmem:
> 
> # devmem 0xfe670040 32 1

Sorry, this should of course have been:
# devmem 0xfe650040 32 1

But the result is the name, no IRQ triggered on the EP side.

(My command above was from testing "msi-parent = <&its0 0x0000>",
rather than &its1, but that also didn't work when writing the
corresponding "doorbell_addr" using e.g. devmem.)

Considering that the RC node is using &its1, that is probably
also what should be used in the EP node when running the controller
in EP mode instead of RC mode.


Kind regards,
Niklas