On Thu, Oct 05, 2017 at 01:59:36PM +0000, [email protected] wrote: > > -----Original Message----- > > From: Andy Shevchenko [mailto:[email protected]] > > Sent: Thursday, October 5, 2017 3:48 AM > > To: Darren Hart <[email protected]> > > Cc: Limonciello, Mario <[email protected]>; LKML <linux- > > [email protected]>; Platform Driver <platform-driver- > > [email protected]>; Andy Lutomirski <[email protected]>; > > [email protected]; Pali Rohár <[email protected]>; Rafael J. Wysocki > > <[email protected]>; [email protected]; Christoph Hellwig <[email protected]>; > > Greg KH <[email protected]> > > Subject: Re: [PATCH v4 05/14] platform/x86: dell-wmi-descriptor: split WMI > > descriptor into it's own driver > > > > On Thu, Oct 5, 2017 at 10:11 AM, Darren Hart <[email protected]> wrote: > > > On Thu, Oct 05, 2017 at 08:29:10AM +0300, Andy Shevchenko wrote: > > >> On Thu, Oct 5, 2017 at 4:09 AM, Darren Hart <[email protected]> wrote: > > > > >> > You'll want to add something like: > > >> > > > >> > #ifdef CONFIG_DELL_WMI_DESCRIPTOR_MODULE > > >> > if (request_module("dell_wmi_descriptor")) > > >> > /* FAIL */ > > >> > #endif > > >> > > > >> > During init. > > >> > > >> I don't think #ifdef is needed. > > > > > > Without the ifdef, we can't distinguish between request_module failing > > > to load the module because it isn't available and because it is > > > built-in. > > > > > >> > > >> We may just request module. > > >> > > >> But looking in the code it seems that we simple need to select that > > >> module. No request_module will be needed. > > > > > > The select will ensure the module is built, but there is not guarantee > > > to module load order. The intent of the above is to ensure the symbols > > > from the required module are loaded. > > > > > >> Did I miss something? > > > > > > Or I did :-) Is there something about this module which ensures > > > dell_wmi_descriptor is loaded first? > > > > If there is an optional *run-time* dependency we need to use somelike > > request_module(). For example, this is the case for idma64 > > (drivers/dma) vs intel-lpss (drivers/mfd). > > > > If it's mandatory run-time dependency, then we need to add stubs to > > the header and select the callee's module in Kconfig. > > > > In case they are both modules, depmod keeps an ordering. > > > > So, the corner case here is when the caller is builtin while callee is > > module. > > > > This is a bit tricky to add to Kconfig (we also have such cases > > between I2C DesignWare and acpi_lpss AFAIR). > > > > -- > > With Best Regards, > > Andy Shevchenko > > So I believe it should be a mandatory runtime dependency due to needing > the symbol dell_wmi_get_interface_version. Depmod should be handling > this then no?
This was nagging me all night, and I was thinking the last time I had to use this it was indeed a runtime dependency. Sorry for the noise on this. The kconfig needs to be setup such that dell-wmi-descriptor cannot be a module if the dependent drivers are modules. -- Darren Hart VMware Open Source Technology Center
