Re: [PATCH v2 0/2] PCI: add enabe(disable)_device() hook for bridge

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Sep 30, 2024 at 03:42:20PM -0400, Frank Li wrote:
> Some system's IOMMU stream(master) ID bits(such as 6bits) less than
> pci_device_id (16bit). It needs add hardware configuration to enable
> pci_device_id to stream ID convert.
> 
> https://lore.kernel.org/imx/20240622173849.GA1432357@bhelgaas/
> This ways use pcie bus notifier (like apple pci controller), when new PCIe
> device added, bus notifier will call register specific callback to handle
> look up table (LUT) configuration.
> 
> https://lore.kernel.org/imx/20240429150842.GC1709920-robh@kernel.org/
> which parse dt's 'msi-map' and 'iommu-map' property to static config LUT
> table (qcom use this way). This way is rejected by DT maintainer Rob.
> 
> Above ways can resolve LUT take or stream id out of usage the problem. If
> there are not enough stream id resource, not error return, EP hardware
> still issue DMA to do transfer, which may transfer to wrong possition.
> 
> Add enable(disable)_device() hook for bridge can return error when not
> enough resource, and PCI device can't enabled.
> 
> Basicallly this version can match Bjorn's requirement:
> 1: simple, because it is rare that there are no LUT resource.
> 2: EP driver probe failure when no LUT, but lspci can see such device.
> 
> [    2.164415] nvme nvme0: pci function 0000:01:00.0
> [    2.169142] pci 0000:00:00.0: Error enabling bridge (-1), continuing
> [    2.175654] nvme 0000:01:00.0: probe with driver nvme failed with error -12
> 
> > lspci
> 0000:00:00.0 PCI bridge: Philips Semiconductors Device 0000
> 0000:01:00.0 Non-Volatile memory controller: Micron Technology Inc 2100AI NVMe SSD [Nitro] (rev 03)
> 
> To: Bjorn Helgaas <bhelgaas@google.com>
> To: Richard Zhu <hongxing.zhu@nxp.com>
> To: Lucas Stach <l.stach@pengutronix.de>
> To: Lorenzo Pieralisi <lpieralisi@kernel.org>
> To: Krzysztof Wilczyński <kw@linux.com>
> To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> To: Rob Herring <robh@kernel.org>
> To: Shawn Guo <shawnguo@kernel.org>
> To: Sascha Hauer <s.hauer@pengutronix.de>
> To: Pengutronix Kernel Team <kernel@pengutronix.de>
> To: Fabio Estevam <festevam@gmail.com>
> Cc: linux-pci@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: imx@lists.linux.dev
> Cc: Frank.li@nxp.com \
> Cc: alyssa@rosenzweig.io \
> Cc: bpf@vger.kernel.org \
> Cc: broonie@kernel.org \
> Cc: jgg@ziepe.ca \
> Cc: joro@8bytes.org \
> Cc: l.stach@pengutronix.de \
> Cc: lgirdwood@gmail.com \
> Cc: maz@kernel.org \
> Cc: p.zabel@pengutronix.de \
> Cc: robin.murphy@arm.com \
> Cc: will@kernel.org \
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> Changes in v2:
> - see each patch
> - Link to v1: https://lore.kernel.org/r/20240926-imx95_lut-v1-0-d0c62087dbab@nxp.com
> 
> ---
> Frank Li (2):
>       PCI: Add enable_device() and disable_device() callbacks for bridges
>       PCI: imx6: Add IOMMU and ITS MSI support for i.MX95
> 
>  drivers/pci/controller/dwc/pci-imx6.c | 133 +++++++++++++++++++++++++++++++++-
>  drivers/pci/pci.c                     |  14 ++++
>  include/linux/pci.h                   |   2 +
>  3 files changed, 148 insertions(+), 1 deletion(-)
> ---
> base-commit: 2849622e7b01d5aea1b060ba3955054798c1e0bb
> change-id: 20240926-imx95_lut-1c68222e0944

Not sure what this applies to; it doesn't apply cleanly to v6.13-rc1
(the pci/main branch).