Re: [PATCH v9 10/15] ACPI: platform-msi: retrieve dev id from IORT

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Wed, Mar 29, 2017 at 03:52:47PM +0100, Marc Zyngier wrote:
> On 29/03/17 14:00, Hanjun Guo wrote:
> > On 03/29/2017 08:38 PM, Lorenzo Pieralisi wrote:
> >> On Wed, Mar 29, 2017 at 07:52:48PM +0800, Hanjun Guo wrote:
> >>> Hi Lorenzo,
> >>>
> >>> On 03/29/2017 06:14 PM, Lorenzo Pieralisi wrote:
> >>>> Hi Hanjun, Marc,
> >>>>
> >>>> On Tue, Mar 07, 2017 at 08:40:05PM +0800, Hanjun Guo wrote:
> >>>>> From: Hanjun Guo <hanjun.guo@linaro.org>
> >>>>>
> >>>>> For devices connecting to ITS, the devices need to identify themself
> >>>>> through a dev id; this dev id is represented in the IORT table in named
> >>>>> component node [1] for platform devices, so this patch adds code that
> >>>>> scans the IORT table to retrieve the devices' dev id.
> >>>>>
> >>>>> Leveraging the iort_node_map_platform_id() IORT API, add a new function
> >>>>> call, iort_pmsi_get_dev_id() and use it in its_pmsi_prepare() to allow
> >>>>> retrieving dev id in ACPI platforms.
> >>>>>
> >>>>> [1]: https://static.docs.arm.com/den0049/b/DEN0049B_IO_Remapping_Table.pdf
> >>>>>
> >>>>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> >>>>> [lorenzo.pieralisi@arm.com: rewrote commit log]
> >>>>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> >>>>> Tested-by: Ming Lei <ming.lei@canonical.com>
> >>>>> Tested-by: Wei Xu <xuwei5@hisilicon.com>
> >>>>> Tested-by: Sinan Kaya <okaya@codeaurora.org>
> >>>>> Cc: Marc Zyngier <marc.zyngier@arm.com>
> >>>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> >>>>> Cc: Tomasz Nowicki <tn@semihalf.com>
> >>>>> Cc: Thomas Gleixner <tglx@linutronix.de>
> >>>>> ---
> >>>>>   drivers/acpi/arm64/iort.c                     | 24 ++++++++++++++++++++++++
> >>>>>   drivers/irqchip/irq-gic-v3-its-platform-msi.c |  3 ++-
> >>>>>   include/linux/acpi_iort.h                     |  5 +++++
> >>>>>   3 files changed, 31 insertions(+), 1 deletion(-)
> >>>>
> >>>> To simplify merging ACPI/IRQCHIP changes via different trees it
> >>>> would be good to split this patch; I am not sure what's the best
> >>>> way of handling it though given that we would end up in a merge
> >>>> ordering dependency anyway (ie we can create an empty stub
> >>>> for iort_pmsi_get_dev_id() but that would create a dependency
> >>>> between ARM64 and irqchip trees anyway).
> >>>
> >>> The first 12 patches for ACPI platform MSI and later 3 patches
> >>> for mbigen have no "physical" dependency, which means they can
> >>> be merged and compiled independently, they only have functional
> >>> dependency only.
> >>>
> >>> We already had SAS, XGE, USB and even UART drivers depend on
> >>> the mbigen ACPI support, so I don't think the dependency of ACPI
> >>> platform MSI and mbigen patches cares much if those two parts are
> >>> merged in one merge window, even they are merged independently via
> >>> different tree.
> >>>
> >>>>
> >>>> Please let me know what's your preferred way of handling this.
> >>>
> >>> So in my opinion, they can be merged independently via ARM64 and
> >>> irqchip tree with no ordering dependency, is it OK?
> >>
> >> I am speaking about merging MBIgen AND ITS patches via IRQCHIP and
> >> ACPI/IORT for ARM64, that's why I replied to this patch. I do not
> >> think that's feasible to split patches in two separate branches
> >> without having a dependency between them.
> >>
> >> Sure, the last three patches can go via IRQCHIP but that was not
> >> my question :)
> > 
> > Sorry, I misunderstood that :(
> > 
> > Since it's not feasible to split patches, the best way I got is that
> > we get Marc's ack then merge it.
> 
> I believe there is a way to make this work without too much hassle. I
> suggest we drop the ITS change from this patch entirely, and I instead
> queue this patch:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/irqchip-4.12&id=e6db07d0f3b6da1f8cfd485776bfefa4fcdbfc45
> 
> That way, no dependency between the two trees. Lorenzo takes all the
> patches flagged "ACPI", I take all those flagged "irqchip" or "msi", and
> everything should be perfectly standalone.
> 
> Thoughts?

Perfect for me. Hanjun, I can cherry pick Marc's patch above, rework
this patch and post the resulting branch for everyone to have a final
test.

Ok ?

Thanks !
Lorenzo