[PATCH v2 1/4] PCI: X-Gene: Add the APM X-Gene v1 PCIe MSI/MSIX termination driver

[Duc Dang]

On Wed, Mar 18, 2015 at 11:52 AM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> On 18/03/15 18:29, Duc Dang wrote:
>> On Wed, Mar 18, 2015 at 11:05 AM, Marc Zyngier <marc.zyngier at arm.com> wrote:
>>> On 04/03/15 19:39, Duc Dang wrote:
>>>> X-Gene v1 SOC supports total 2688 MSI/MSIX vectors coalesced into
>>>> 16 HW IRQ lines.
>>>>
>>>> Signed-off-by: Duc Dang <dhdang at apm.com>
>>>> Signed-off-by: Tanmay Inamdar <tinamdar at apm.com>
>>>
>>> I just had a quick look at this, and this seems to be going in the exact
>>> opposite direction compared to what we now have on arm64, where we move
>>> away from using struct msi_controller for most thing, and implement PCI
>>> MSI/MSIX in a generic way, using MSI domains.
>>>
>>> I suggest you have a look at how GICv2m and GICv3 ITS implement the MSI
>>> support. You can also have a look at what I did for the Tegra MSI
>>> controller in this patch:
>>>
>>> https://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/kill-msi-controller&id=83b3602fcee7972b9d549ed729b56ec28de16081
>>>
>>> Eventually, the plan is to kill msi_controller entirely, so introducing
>>> new drivers that rely on it is not something I'm eager to see.
>>
>> Thanks, Marc.
>>
>>  X-Gene 1 MSI is handled by separate MSI controller block, so its
>> driver implementation is different from GICv2m and GICv3. I will refer
>
> It will certainly be different in the sense that you won't use a stacked
> domain on top of the GIC. But what I want to see is the use of a generic
> pci_msi_domain on top of an irq_domain, just like we have on v2m and v3.
> Thomas has also been vocal enough about that in the past, and x86 is
> going down that road as well.
>
>> to what you did for Tegra MSI, but I don't see your latest changes in
>> 4.0-rc4. Is the change you made for Tegra MSI going to mainline soon?
>
> Not yet. As you can see in this branch, this relies on some other
> cleanups. But you can already convert most of your driver and put it in
> the shape that matches what we have for v2m and v3. Once the required
> cleanups are in, I'll remove the last traces of msi_controller myself if
> necessary.
>

Hi Marc, Bjorn,

I follow Marc's suggestion and convert my X-Gene 1 MSI driver to
remove msi_controller struct and use generic pci_msi_domain on top of
an irq_domain. The code requires Marc's changes in
irq/kill-msi-controller branch to be compiled and function correctly,
so I plan to post the patch on top of Marc's tree. Please let me know
if you think I should have different approach to post this patch.

Another question I have is when do you plan to roll out this hierarchy
irq domain implementation for MSI, as I see some of Marc's changes to
kill msi_controller structure and implement MSI irq domain still does
not get into Bjorn's tree.

Regards,
Duc Dang.

> Thanks,
>
>         M.
> --
> Jazz is not dead. It just smells funny...