Re: [PATCH v2 0/5] Add RC-to-EP doorbell with platform MSI controller

[Niklas Cassel <cassel@kernel.org>]

On Mon, Sep 11, 2023 at 06:09:15PM -0400, Frank Li wrote:
> ┌────────────┐   ┌───────────────────────────────────┐   ┌────────────────┐
> │            │   │                                   │   │                │
> │            │   │ PCI Endpoint                      │   │ PCI Host       │
> │            │   │                                   │   │                │
> │            │◄──┤ 1.platform_msi_domain_alloc_irqs()│   │                │
> │            │   │                                   │   │                │
> │ MSI        ├──►│ 2.write_msi_msg()                 ├──►├─BAR<n>         │
> │ Controller │   │   update doorbell register address│   │                │
> │            │   │   for BAR                         │   │                │
> │            │   │                                   │   │ 3. Write BAR<n>│
> │            │◄──┼───────────────────────────────────┼───┤                │
> │            │   │                                   │   │                │
> │            ├──►│ 4.Irq Handle                      │   │                │
> │            │   │                                   │   │                │
> │            │   │                                   │   │                │
> └────────────┘   └───────────────────────────────────┘   └────────────────┘
> 
> This patches based on old https://lore.kernel.org/imx/20221124055036.1630573-1-Frank.Li@nxp.com/
> 
> Original patch only target to vntb driver. But actually it is common
> method.
> 
> This patches add new API to pci-epf-core, so any EP driver can use it.
> 
> The key point is comments from Thomas Gleixner, who suggest use new
> PCI/IMS. But arm platform change still not be merged yet.
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git devmsi-v2-arm
> 
> So I still use existed method implement RC to EP doorbell.
> 
> If Thomas Gleixner want to continue work on devmsi-v2-arm, I can help test
> and update this patch.
> 
> Change from v1 to v2
> - Add missed patch for endpont/pci-epf-test.c
> - Move alloc and free to epc driver from epf.
> - Provide general help function for EPC driver to alloc platform msi irq.
> - Fixed manivannan's comments.
> 
> Frank Li (5):
>   PCI: endpoint: Add RC-to-EP doorbell support using platform MSI
>     controller
>   PCI: dwc: add doorbell support by use MSI controller
>   PCI: endpoint: pci-epf-test: add doorbell test
>   misc: pci_endpoint_test: Add doorbell test case
>   tools: PCI: Add 'B' option for test doorbell
> 
>  drivers/misc/pci_endpoint_test.c              |  48 +++++
>  .../pci/controller/dwc/pcie-designware-ep.c   |   2 +
>  drivers/pci/endpoint/functions/pci-epf-test.c |  59 +++++-
>  drivers/pci/endpoint/pci-epc-core.c           | 192 ++++++++++++++++++
>  drivers/pci/endpoint/pci-epf-core.c           |  44 ++++
>  include/linux/pci-epc.h                       |   6 +
>  include/linux/pci-epf.h                       |   7 +
>  include/uapi/linux/pcitest.h                  |   1 +
>  tools/pci/pcitest.c                           |  16 +-
>  9 files changed, 373 insertions(+), 2 deletions(-)
> 
> -- 
> 2.34.1
> 

Hello Frank,

Thank you for your work on this.
This series is very interesting.

As you probably know, IMS support was ripped out of the kernel a few
months ago:
b966b1102871 ("Revert "PCI/MSI: Provide IMS (Interrupt Message Store) support"")

So this series seems as relevant as ever.

Are you considering continuing work on this series any time soon?


Kind regards,
Niklas