> -----Original Message----- > From: Andy Shevchenko [mailto:andy.shevchenko@xxxxxxxxx] > Sent: Thursday, October 5, 2017 3:48 AM > To: Darren Hart <dvhart@xxxxxxxxxxxxx> > Cc: Limonciello, Mario <Mario_Limonciello@xxxxxxxx>; LKML <linux- > kernel@xxxxxxxxxxxxxxx>; Platform Driver <platform-driver- > x86@xxxxxxxxxxxxxxx>; Andy Lutomirski <luto@xxxxxxxxxx>; > quasisec@xxxxxxxxxx; Pali Rohár <pali.rohar@xxxxxxxxx>; Rafael J. Wysocki > <rjw@xxxxxxxxxxxxx>; mjg59@xxxxxxxxxx; Christoph Hellwig <hch@xxxxxx>; > Greg KH <greg@xxxxxxxxx> > 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 <dvhart@xxxxxxxxxxxxx> 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 <dvhart@xxxxxxxxxxxxx> 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?
