Re: [PATCH v9 0/2] PCI: add enabe(disable)_device() hook for bridge

[Bjorn Helgaas]

On Wed, Jan 15, 2025 at 08:58:50AM +0000, Marc Zyngier wrote:
> On Tue, 14 Jan 2025 22:33:41 +0000,
> Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> > 
> > On Tue, Jan 14, 2025 at 03:37:07PM -0500, 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@xxxxxxxxxx/
> > > 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@xxxxxxxxxx>
> > > To: Richard Zhu <hongxing.zhu@xxxxxxx>
> > > To: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> > > To: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
> > > To: Krzysztof Wilczyński <kw@xxxxxxxxx>
> > > To: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > > To: Rob Herring <robh@xxxxxxxxxx>
> > > To: Shawn Guo <shawnguo@xxxxxxxxxx>
> > > To: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > > To: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> > > To: Fabio Estevam <festevam@xxxxxxxxx>
> > > Cc: linux-pci@xxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > Cc: imx@xxxxxxxxxxxxxxx
> > > Cc: Frank.li@xxxxxxx \
> > > Cc: alyssa@xxxxxxxxxxxxx \
> > > Cc: bpf@xxxxxxxxxxxxxxx \
> > > Cc: broonie@xxxxxxxxxx \
> > > Cc: jgg@xxxxxxxx \
> > > Cc: joro@xxxxxxxxxx \
> > > Cc: l.stach@xxxxxxxxxxxxxx \
> > > Cc: lgirdwood@xxxxxxxxx \
> > > Cc: maz@xxxxxxxxxx \
> > > Cc: p.zabel@xxxxxxxxxxxxxx \
> > > Cc: robin.murphy@xxxxxxx \
> > > Cc: will@xxxxxxxxxx \
> > > Cc: Robin Murphy <robin.murphy@xxxxxxx>
> > > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > > 
> > > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > 
> > Applied to pci/controller/imx6 for v6.14, thanks!  And thanks for your
> > patience.
> 
> While you're at it, could you please consider [1], which builds on top
> of the same infrastructure to remove the Apple PCIe IOMMU hack?
> 
> [1] https://lore.kernel.org/linux-pci/20241204150145.800408-1-maz@xxxxxxxxxx/

Done, thanks for the reminder!