Re: [PATCH v4 1/2] PCI: Add enable_device() and disable_device() callbacks for bridges

[Marc Zyngier <maz@kernel.org>]

On Fri, 01 Nov 2024 21:04:39 +0000,
Frank Li <Frank.Li@nxp.com> wrote:
> 
> Some PCIe host bridges require special handling when enabling or disabling
> PCIe Endpoints. For example, the i.MX95 platform has a lookup table to map
> Requester IDs to StreamIDs, which are used by the SMMU and MSI controller
> to identify the source of DMA accesses.
> 
> Without this mapping, DMA accesses may target unintended memory, which
> would corrupt memory or read the wrong data.
> 
> Add a host bridge .enable_device() hook the imx6 driver can use to
> configure the Requester ID to StreamID mapping. The hardware table isn't
> big enough to map all possible Requester IDs, so this hook may fail if no
> table space is available. In that case, return failure from
> pci_enable_device().
> 
> It might make more sense to make pci_set_master() decline to enable bus
> mastering and return failure, but it currently doesn't have a way to return
> failure.
> 
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>

I converted the fruity PCIe controller over to this infrastructure,
and things seem to work fine. FWIW:

Reviewed-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.