On Fri, Feb 14, 2020 at 04:35:10PM +0000, Pankaj Bansal wrote: [...] > > -----Original Message----- > > From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > > Sent: Friday, February 14, 2020 9:50 PM > > To: Pankaj Bansal <pankaj.bansal@xxxxxxx> > > Cc: Marc Zyngier <maz@xxxxxxxxxx>; Ard Biesheuvel > > <ard.biesheuvel@xxxxxxxxxx>; Makarand Pawagi <makarand.pawagi@xxxxxxx>; > > Calvin Johnson <calvin.johnson@xxxxxxx>; stuyoder@xxxxxxxxx; > > nleeder@xxxxxxxxxxxxxx; Ioana Ciornei <ioana.ciornei@xxxxxxx>; Cristi > > Sovaiala <cristian.sovaiala@xxxxxxx>; Hanjun Guo <guohanjun@xxxxxxxxxx>; > > Will Deacon <will@xxxxxxxxxx>; jon@xxxxxxxxxxxxx; Russell King > > <linux@xxxxxxxxxxxxxxx>; ACPI Devel Maling List <linux-acpi@xxxxxxxxxxxxxxx>; > > Len Brown <lenb@xxxxxxxxxx>; Jason Cooper <jason@xxxxxxxxxxxxxx>; Andy > > Wang <Andy.Wang@xxxxxxx>; Varun Sethi <V.Sethi@xxxxxxx>; Thomas > > Gleixner <tglx@xxxxxxxxxxxxx>; linux-arm-kernel <linux-arm- > > kernel@xxxxxxxxxxxxxxxxxxx>; Laurentiu Tudor <laurentiu.tudor@xxxxxxx>; Paul > > Yang <Paul.Yang@xxxxxxx>; netdev@xxxxxxxxxxxxxxx; Rafael J. Wysocki > > <rjw@xxxxxxxxxxxxx>; Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; > > Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>; > > Sudeep Holla <sudeep.holla@xxxxxxx>; Robin Murphy > > <robin.murphy@xxxxxxx> > > Subject: Re: [EXT] Re: [PATCH] bus: fsl-mc: Add ACPI support for fsl-mc Side note: would you mind removing the email headers (as above) in your replies please ? > > On Fri, Feb 14, 2020 at 03:58:14PM +0000, Pankaj Bansal wrote: > > > > [...] > > > > > > Why should the device know about its own ID? That's a bus/interconnect > > thing. > > > > And nothing should be passed *to* IORT. IORT is the source. > > > > > > IORT is translation between Input IDs <-> Output IDs. The Input ID is still > > expected to be passed to parse IORT table. > > > > Named components use an array of single mappings (as in entries with single > > mapping flag set) - Input ID is irrelevant. > > > > Not sure what your named component is though and what you want to do with > > it, the fact that IORT allows mapping for named components do not necessarily > > mean that it can describe what your system really is, on that you need to > > elaborate for us to be able to help. > > Details about MC bus can be read from here: > https://elixir.bootlin.com/linux/latest/source/Documentation/networking/device_drivers/freescale/dpaa2/overview.rst#L324 > > As stated above, in Linux MC is a bus (just like PCI bus, AMBA bus etc) > There can be multiple devices attached to this bus. Moreover, we can dynamically create/destroy these devices. > Now, we want to represent this BUS (not individual devices connected to bus) in IORT table. > The only possible way right now we see is that we describe it as Named components having a pool of ID mappings. > As and when devices are created and attached to bus, we sift through this pool to correctly determine the output ID for the device. > Now the input ID that we provide, can come from device itself. > Then we can use the Platform MSI framework for MC bus devices. So are you asking me if that's OK ? Or there is something you can't describe with IORT ? Side note: can you explain to me please how the MSI allocation flow and kernel data structures/drivers are modeled in DT ? I had a quick look at: drivers/irqchip/irq-gic-v3-its-fsl-mc-msi.c and to start with, does that code imply that we create a DOMAIN_BUS_FSL_MC_MSI on ALL DT systems with an ITS device node ? I *think* you have a specific API to allocate MSIs for MC devices: fsl_mc_msi_domain_alloc_irqs() which hook into the IRQ domain created in the file above that handles the cascading to an ITS domain, correct ? Thanks, Lorenzo
