On 03/01/2013 03:41 PM, Guenter Roeck wrote: > On Fri, Mar 01, 2013 at 02:38:30PM +0100, Lars-Peter Clausen wrote: >> On 03/01/2013 05:32 AM, Guenter Roeck wrote: >>> Hi all, >>> >>> IIO_TRIGGERED_BUFFER depends on IIO_BUFFER because of: >>> >>> drivers/iio/industrialio-triggered-buffer.c:20:16: error: >>> ‘iio_sw_buffer_preenable’ undeclared here (not in a function) >>> >>> On the other side, it is often selected as follows. >>> >>> select IIO_TRIGGERED_BUFFER if (IIO_BUFFER) >>> >>> For that reason, selecting IIO_BUFFER in the IIO_TRIGGERED_BUFFER declaration >>> results in a circular dependency. Sometimes the "if (IIO_BUFFER)" when selecting >>> IIO_TRIGGERED_BUFFER is missing, though, which can result in the compile error. >>> >>> What is the proper solution ? >>> - Add "if (IIO_BUFFER)" whenever IIO_TRIGGERED_BUFFER is selected >>> or >>> - Remove "if (IIO_BUFFER)" from IIO_TRIGGERED_BUFFER selection and add "select >>> IIO_BUFFER" to the IIO_TRIGGERED_BUFFER declaration >>> >>> I would prefer the latter to solve the problem for good. >> >> Hi, >> >> This is a bit tricky, some drivers have optional buffer support, so they >> only select the helper module if buffer support is enabled, since they don't >> use the helper module if buffer support is disabled. Other driver though >> always want buffer support so they select the helper module unconditionally. >> So far it was the responsibility of the driver's Kconfig entry to make sure >> that if it selects IIO_TRIGGERED_BUFFER it needs to make sure that >> IIO_BUFFER is also selected. As far as I can see all drivers do this >> currently. Which one breaks things for you? >> > It is a randconfig thing, so it breaks in some of my nightly randconfig builds, > and it has also been reported as build failure in the official builds. I can dig > out some affected configurations and send it to you if you like. Yes that would be great, thanks. > but the gist of > it is that IIO_TRIGGERED_BUFFER can be selected without IIO_BUFFER, but depends > on it. That just isn't correct. Of course, the other option might be to make > IIO_TRIGGERED_BUFFER dependent on IIO_BUFFER. Would that be acceptable ? > That won't work, you can overwrite 'depends on' by selecting the symbol. But the reason why there is a cyclic dependency is not because of the 'select IIO_TRIGGERED_BUFFER if (IIO_BUFFER)' but rather because IIO_TRIGGERED_BUFFER is in an 'if IIO_BUFFER' section. Moving it out there fixes the cyclic dependency error. But creates a recursive dependency warning. I think we could avoid this warning by introducing a new symbol. E.g. IIO_BUFFER_INTERN (bad name). IIO_BUFFER_INTERN won't be user selectable. It will be selected by IIO_BUFFER and IIO_TRIGGERED_BUFFER and if it is selected buffer support is built. E.g. something like this: diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig index b2f963b..f7bf173 100644 --- a/drivers/iio/Kconfig +++ b/drivers/iio/Kconfig @@ -14,11 +14,15 @@ if IIO config IIO_BUFFER bool "Enable buffer support within IIO" + select IIO_BUFFER_INTERN help Provide core support for various buffer based data acquisition methods. -if IIO_BUFFER +config IIO_BUFFER_INTERN + bool + +if IIO_BUFFER_INTERN config IIO_BUFFER_CB boolean "IIO callback buffer used for push in-kernel interfaces" @@ -35,15 +39,16 @@ config IIO_KFIFO_BUF no buffer events so it is up to userspace to work out how often to read from the buffer. +endif # IIO_BUFFER + config IIO_TRIGGERED_BUFFER tristate select IIO_TRIGGER select IIO_KFIFO_BUF + select IIO_BUFFER_INTERN help Provides helper functions for setting up triggered buffers. -endif # IIO_BUFFER - config IIO_TRIGGER boolean "Enable triggered sampling support" help diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile index a0e8cdd..a43df71 100644 --- a/drivers/iio/Makefile +++ b/drivers/iio/Makefile @@ -4,7 +4,7 @@ obj-$(CONFIG_IIO) += industrialio.o industrialio-y := industrialio-core.o industrialio-event.o inkern.o -industrialio-$(CONFIG_IIO_BUFFER) += industrialio-buffer.o +industrialio-$(CONFIG_IIO_BUFFER_INTERN) += industrialio-buffer.o industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o industrialio-$(CONFIG_IIO_BUFFER_CB) += buffer_cb.o Although this has the downside that it is not immediately visible anymore whether buffer support is going to be built or not. - Lars -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
