On Wed, Oct 20, 2010 at 1:53 AM, Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> wrote: >> And to allow early board code to reserve specific hwspinlock numbers >> for predefined use-cases, we probably want to be before arch_initcall. > > There's no reason for board code to have to do this at initcall time. If we want to have allow both allocations of predefined hwspinlocks with omap_hwspinlock_request_specific(int), and dynamic allocations (where we don't care about the specific instance of the hwspinlock we will get) with omap_hwspinlock_request(), we must ensure that the former _specific() API will never be called after the latter. If we will allow drivers to call omap_hwspinlock_request() before all callers of omap_hwspinlock_request_specific() completed, then things will break (because drivers might start getting hwspinlocks that are predefined for dedicated use cases on the system). So if we want the _specific API to work, we can only allow early board code to use it in order to reserve those predefined hwspinlocks before drivers get the chance to call omap_hwspinlock_request(). The tempting alternative is not to provide the omap_hwspinlock_request_specific() API at all (which is something we discussed internally). Let's take the i2c-omap for example. It sounds like it must have a predefined hwspinlock, but what if: 1. It will use omap_hwspinlock_request() to dynamically allocate a hwspinlock 2. Obviously, the hwspinlock id number must be communicated to the M3 BIOS, so the i2c-omap will publish that id using a small shared memory entry that will be allocated for this sole purpose 3. we will make sure that 1+2 completes before the remote processor is taken out of reset This does not require any smart IPC and it will allow us to get rid of the omap_hwspinlock_request_specific() API and its early-callers requirement. All we will be left to take care of is the order of the ->probe() execution (assuming we want both the i2c and the hwspinlock drivers to be device_initcall) > > This kind of thing needs to be done by platform_data function pointers, > as is done for every other driver that needs platform-specific driver > customization. Why would we need platform-specific function pointers here ? I'm not sure I'm following this one. Thanks, Ohad. > > Kevin > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
