On Tue, Jun 24, 2025 at 04:38:25PM +0100, Greg KH wrote: > On Tue, Jun 24, 2025 at 04:36:35PM +0100, Greg KH wrote: > > On Tue, Jun 24, 2025 at 04:27:21PM +0300, Dmitry Baryshkov wrote: > > > On Thu, Jun 19, 2025 at 10:40:26AM +0530, Ekansh Gupta wrote: > > > > During rpmsg_probe, fastrpc device nodes are created first, then > > > > channel specific resources are initialized, followed by > > > > of_platform_populate, which triggers context bank probing. This > > > > sequence can cause issues as applications might open the device > > > > node before channel resources are initialized or the session is > > > > available, leading to problems. For example, spin_lock is initialized > > > > after the device node creation, but it is used in device_open, > > > > potentially before initialization. Move device registration after > > > > channel resource initialization in fastrpc_rpmsg_probe. > > > > > > You've moved device init, however there is still a possibility for the > > > context devices to be created, but not bound to the driver (because all > > > the probings are async). I think instead we should drop the extra > > > platform driver layer and create and set up corresponding devices > > > manually. For example, see how it is handled in > > > host1x_memory_context_list_init(). That function uses iommu-maps, but we > > > can use OF nodes and iommus instead. > > > > Is this a real platform device? If so, why do you need a second > > platform driver, what makes this so unique? If this isn't a platform > > device, then why not just use the faux bus instead? > > > > It seems that "number of sessions" is a DT property, is that something > > that is really defined by the hardware? Or is it just a virtual thing > > that people are abusing in the DT?
Purely software value. > > > > And if you really have all these sessions, why not make them real > > devices, wouldn't that make things simpler? > > Oh wait, these are "fake" platform devices under the parent (i.e. real) > platform device. That's not good, please don't do that, use the faux > bus code now instead to properly handle this. Attempting to create a > device when open() is called is really really odd... The driver doesn't created devices during open(). It creates them earlier, then another driver probes an populates the data. I suggest to follow Tegra approach, remove the sub-driver completely and instead of calling of_platform_populate() create necessary devices manually and set corresponding IOMMU configuration from the main driver's probe path. -- With best wishes Dmitry
