> -----Original Message----- > From: Darren Hart [mailto:dvhart@xxxxxxxxxxxxx] > Sent: Thursday, October 5, 2017 9:15 AM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: andy.shevchenko@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; platform- > driver-x86@xxxxxxxxxxxxxxx; luto@xxxxxxxxxx; quasisec@xxxxxxxxxx; > pali.rohar@xxxxxxxxx; rjw@xxxxxxxxxxxxx; mjg59@xxxxxxxxxx; hch@xxxxxx; > greg@xxxxxxxxx > Subject: Re: [PATCH v4 05/14] platform/x86: dell-wmi-descriptor: split WMI > descriptor into it's own driver > > On Thu, Oct 05, 2017 at 01:59:36PM +0000, Mario.Limonciello@xxxxxxxx wrote: > > > -----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? > > 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 Even if the others are modules shouldn't module ordering from depmod still DTRT? You still won't be able to load dell-wmi.ko until dell-wmi-descriptor.ko was loaded.
