Re: [PATCH V6 2/3] ACPI: Add support for ResourceSource/IRQ domain mapping

[agustinv]

Hey Lorenzo, Hanjun,

On 2016-11-11 08:33, Hanjun Guo wrote:
> Hi Lorenzo,
>
> On 11/11/2016 01:58 AM, Lorenzo Pieralisi wrote:
> > On Thu, Nov 10, 2016 at 10:02:35AM -0500, agustinv@xxxxxxxxxxxxxx 
> > wrote:
> > > Hey Hanjun,
> > >
> > > On 2016-11-09 21:36, Hanjun Guo wrote:
> > > > Hi Marc, Rafael, Lorenzo,
> > > >
> > > > Since we agreed to add a probe deferral if we failed to get irq
> > > > resources which mirroring the DT does (patch 1 in this patch set),
> > > > I think the last blocker to make things work both for Agustin and
> > > > me [1] is this patch, which makes the interrupt producer and 
> > > > consumer
> > > > work in ACPI, we have two different solution for one thing, we'd 
> > > > happy
> > > > to work together for one solution, could you give some suggestions
> > > > please?
> > > >
> > > > [1]: 
> > > > https://mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1257419.html
> > > >
> > > > Agustin, I have some comments below.
> > > >
> > > > On 2016/10/29 4:48, Agustin Vega-Frias wrote:
> > > > > This allows irqchip drivers to associate an ACPI DSDT device to
> > > > > an IRQ domain and provides support for using the ResourceSource
> > > > > in Extended IRQ Resources to find the domain and map the IRQs
> > > > > specified on that domain.
> > > > >
> > > > > Signed-off-by: Agustin Vega-Frias <agustinv@xxxxxxxxxxxxxx>
> > > > > ---
> > > > > drivers/acpi/Makefile    |   1 +
> > > > > drivers/acpi/irqdomain.c | 119
> > > > > +++++++++++++++++++++++++++++++++++++++++++++++
> > > >
> > > > Could we just reuse the gsi.c and not introduce a new
> > > > file, probably we can change the gsi.c to irqdomain.c
> > > > or something similar, then reuse the code in gsi.c.
> > >
> > > I was thinking just that after we chatted off-list.
> >
> > Yes, that's a fair point.
> >
> > > I might revisit and see what I come up with given that we already 
> > > have
> > > a device argument and we could pass the IRQ source there.
> >
> > I agree with the approach taken by this patch, I do not like much
> > passing around struct acpi_resource_source *source (in particular
> > the dummy struct) I do not think it is needed, I will comment on
> > the code.
>
> thanks for your time to have a look:)
>
> > Hopefully there is not any buggy FW out there that does use the
> > resource source inappropriately otherwise we will notice on x86/ia64
> > (ie you can't blame FW if it breaks the kernel) but I suspect the
> > only way to find out is by trying, the patch has to go through 
> > Rafael's
> > review anyway before getting there so it is fine.
>
> I think we can avoid that by not touching the logic that x86/ia64
> already used, but only adding interrupt producer/consumer function.

I looked at this more today and implemented a new patch that I plan to
test over the weekend, but I wanted to let you know the approach I am
pursuing.

On the new patch use of ResourceSource when parsing ACPI Extended IRQ
Resources is conditional on CONFIG_ACPI_GENERIC_GSI. The reason for this
is two fold:

1. Since we wanted to reduce duplication and place the new APIs on the
   same source file as acpi_register_gsi, which is already under that
   config flag.
2. So the patch does not have effect on platforms not using the generic
   GSI support, including x86/ia64.

If support for this is needed outside platforms using the generic GSI
implementation, we can move these APIs out to their own source file
and eliminate the CONFIG_ACPI_GENERIC_GSI conditionality.

I'll send the new patch, hopefully some time tomorrow, but please let
me know if you have concerns with this approach.

Thanks,
Agustin

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