> -----Original Message----- > From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > Sent: Tuesday, April 14, 2020 8:02 PM > To: Laurentiu Tudor <laurentiu.tudor@xxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; > robin.murphy@xxxxxxx; ard.biesheuvel@xxxxxxxxxx; Ioana Ciornei > <ioana.ciornei@xxxxxxx>; Diana Madalina Craciun (OSS) > <diana.craciun@xxxxxxxxxxx>; maz@xxxxxxxxxx; jon@xxxxxxxxxxxxx; Pankaj > Bansal <pankaj.bansal@xxxxxxx>; Makarand Pawagi > <makarand.pawagi@xxxxxxx>; Calvin Johnson <calvin.johnson@xxxxxxx>; > Varun Sethi <V.Sethi@xxxxxxx>; Cristi Sovaiala <cristian.sovaiala@xxxxxxx>; > Stuart.Yoder@xxxxxxx; jeremy.linton@xxxxxxx; joro@xxxxxxxxxx; > tglx@xxxxxxxxxxxxx; jason@xxxxxxxxxxxxxx > Subject: [EXT] Re: [RFC PATCH 1/4] bus: fsl-mc: add custom .dma_configure > implementation > > Caution: EXT Email > > On Wed, Mar 25, 2020 at 06:48:55PM +0200, Laurentiu Tudor wrote: > > Hi Lorenzo, > > > > On 3/25/2020 2:51 PM, Lorenzo Pieralisi wrote: > > > On Thu, Feb 27, 2020 at 12:05:39PM +0200, laurentiu.tudor@xxxxxxx wrote: > > >> From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx> > > >> > > >> The devices on this bus are not discovered by way of device tree > > >> but by queries to the firmware. It makes little sense to trick the > > >> generic of layer into thinking that these devices are of related so > > >> that we can get our dma configuration. Instead of doing that, add > > >> our custom dma configuration implementation. > > >> > > >> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@xxxxxxx> > > >> --- > > >> drivers/bus/fsl-mc/fsl-mc-bus.c | 31 > > >> ++++++++++++++++++++++++++++++- > > >> 1 file changed, 30 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c > > >> b/drivers/bus/fsl-mc/fsl-mc-bus.c index 36eb25f82c8e..eafaa0e0b906 > > >> 100644 > > >> --- a/drivers/bus/fsl-mc/fsl-mc-bus.c > > >> +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c > > >> @@ -132,11 +132,40 @@ static int fsl_mc_bus_uevent(struct device > > >> *dev, struct kobj_uevent_env *env) static int > > >> fsl_mc_dma_configure(struct device *dev) { > > >> struct device *dma_dev = dev; > > >> + struct iommu_fwspec *fwspec; > > >> + const struct iommu_ops *iommu_ops; struct fsl_mc_device *mc_dev > > >> + = to_fsl_mc_device(dev); int ret; > > >> + u32 icid; > > >> > > >> while (dev_is_fsl_mc(dma_dev)) > > >> dma_dev = dma_dev->parent; > > >> > > >> - return of_dma_configure(dev, dma_dev->of_node, 0); > > >> + fwspec = dev_iommu_fwspec_get(dma_dev); if (!fwspec) > > >> + return -ENODEV; > > >> + iommu_ops = iommu_ops_from_fwnode(fwspec->iommu_fwnode); > > >> + if (!iommu_ops) > > >> + return -ENODEV; > > >> + > > >> + ret = iommu_fwspec_init(dev, fwspec->iommu_fwnode, iommu_ops); > > >> + if (ret) > > >> + return ret; > > >> + > > >> + icid = mc_dev->icid; > > >> + ret = iommu_fwspec_add_ids(dev, &icid, 1); > > > > > > I see. So with this patch we would use the MC named component only > > > to retrieve the iommu_ops > > > > Right. I'd also add that the implementation tries to follow the > > existing standard .dma_configure implementations, e.g. > > of_dma_configure + of_iommu_configure. I'd also note that similarly to > > the ACPI case, this MC FW device is probed as a platform device in the > > DT scenario, binding here [1]. > > A similar approach is used for the retrieval of the msi irq domain, > > see following patch. > > > > > - the streamid are injected directly here bypassing OF/IORT bindings > translations altogether. > > > > Actually I've submitted a v2 [2] that calls into .of_xlate() to allow > > the smmu driver to do some processing on the raw streamid coming from > > the firmware. I have not yet tested this with ACPI but expect it to > > work, however, it's debatable how valid is this approach in the > > context of ACPI. > > Actually, what I think you need is of_map_rid() (and an IORT equivalent, that I > am going to write - generalizing iort_msi_map_rid()). > That would help. > Would that be enough to enable IORT "normal" mappings in the MC bus named > components ? > But still the question remain unanswered that how we are going to represent MC? As Platform device with single ID mapping flag? > Thanks, > Lorenzo