On Mon, Feb 17, 2020 at 12:35:12PM +0000, Pankaj Bansal wrote: > > > > -----Original Message----- > > From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > > Sent: Friday, February 14, 2020 11:20 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 > > > > 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 ? Read the question above please. [...] > > > 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 ? > > I am asking if that would be acceptable? > i.e. we represent MC bus as Named component is IORT table with a pool of IDs (without single ID mapping flag) > and then we use the Platform MSI framework for all children devices of MC bus. > Note that it would require the Platform MSI layer to correctly pass an input id for a platform device to IORT layer. How is this solved in DT ? You don't seem to need any DT binding on top of the msi-parent property, which is equivalent to IORT single mappings AFAICS so I would like to understand the whole DT flow (so that I understand how this FSL bus works) before commenting any further. > And IORT layer ought to retrieve the output id based on single ID mapping flag as well as input id. > > > > > 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 ? > > Yes. It's being done for all DT systems having ITS node. This does not seem correct to me, I will let Marc comment on the matter. > The domain creation is handled in drivers/bus/fsl-mc/fsl-mc-msi.c Thanks, Lorenzo
