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Subject: Re: [PATCH 0/3] PCI/gic-v3-its: Add support for same ITS device ID
 for multiple PCIe devices
To:     Marc Zyngier <maz@kernel.org>
CC:     Thomas Gleixner <tglx@linutronix.de>,
        Bjorn Helgaas <bhelgaas@google.com>,
        <linux-kernel@vger.kernel.org>, <linux-pci@vger.kernel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        <lokeshvutla@ti.com>
References: <20210920064133.14115-1-kishon@ti.com>
 <871r5jwqw3.wl-maz@kernel.org>
From:   Kishon Vijay Abraham I <kishon@ti.com>
Message-ID: <96caa71f-2632-6eb7-e211-1c2f43a3be16@ti.com>
Date:   Mon, 20 Sep 2021 16:52:48 +0530
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Hi Marc,

On 20/09/21 2:44 pm, Marc Zyngier wrote:
> On Mon, 20 Sep 2021 07:41:30 +0100,
> Kishon Vijay Abraham I <kishon@ti.com> wrote:
>>
>> AM64 has an issue in that it doesn't trigger interrupt if the address
>> in the *pre_its_window* is not aligned to 8-bytes (this is due to an
>> invalid bridge configuration in HW).
>>
>> This means there will not be interrupts for devices with PCIe
>> requestor ID 0x1, 0x3, 0x5..., as the address in the pre-ITS window
>> would be 4 (1 << 2), 12 (3 << 2), 20 (5 << 2) respectively which are
>> not aligned to 8-bytes.
>>
>> The DT binding has specified "msi-map-mask" using which multiple PCIe
>> devices could be made to use the same ITS device ID.
>>
>> Add support in irq-gic-v3-its-pci-msi.c for such cases where multiple
>> PCIe devices are using the same ITS device ID.
>>
>> Kishon Vijay Abraham I (3):
>>   PCI: Add support in pci_walk_bus() to invoke callback matching RID
>>   PCI: Export find_pci_root_bus()
>>   irqchip/gic-v3-its: Include "msi-map-mask" for calculating nvecs
>>
>>  drivers/irqchip/irq-gic-v3-its-pci-msi.c | 21 ++++++++++++++++++++-
>>  drivers/pci/bus.c                        | 13 +++++++++----
>>  drivers/pci/host-bridge.c                |  3 ++-
>>  include/linux/pci.h                      |  8 ++++++--
>>  4 files changed, 37 insertions(+), 8 deletions(-)
> 
> What I don't see in this series is how you address the other part of
> the problem, which is your reuse of the Socionext hack. Please post a
> complete series addressing all the issues for this HW.

No additional patches are pending. Socionext configuration is used as is
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/ti/k3-am64-main.dtsi#n72

FWIW the issue that I address in this series is not observed with standalone USB
cards or NVMe cards. The issue was observed when I tried with a multi-function
PCIe card.

Thank You,
Kishon