Re: [PATCH v1 1/3] driver core: Split device data types to device/types.h

[Greg Kroah-Hartman]

On Tue, Feb 24, 2026 at 04:01:38PM +0200, Andy Shevchenko wrote:
> On Tue, Feb 24, 2026 at 01:21:10PM +0100, Rafael J. Wysocki wrote:
> > On Tue, Feb 24, 2026 at 10:05 AM Andy Shevchenko
> > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > On Mon, Feb 23, 2026 at 09:53:17PM +0100, Rafael J. Wysocki wrote:
> > > > On Mon, Feb 23, 2026 at 9:44 PM Andy Shevchenko
> > > > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > > >
> > > > > device.h is a huge header which is hard to follow and easy to miss
> > > > > something. Improve that by splitting device data types to device/types.h.
> > > > >
> > > > > In particular this helps to speedup the build of the code that includes
> > > > > device.h solely for a device data types.
> > > > >
> > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > > >
> > > > But why do you want to move the struct device definition out of device.h?
> > >
> > > Because it's a data type, and we have many drivers that may require it
> > > (embed the struct device), but no device.h API is called directly —
> > > only via a certain framework).
> > >
> > > device.h also includes many unrelated headers in such a case.
> > 
> > Why is this a problem?
> > 
> > Could those headers be moved to different header files instead?
> > 
> > device.h is mostly about the struct device definition and the other
> > stuff in it is more or less additional.  Why do you want to make it
> > the other way around?
> 
> It's a common trend in the kernel to split out _types.h and _api.h
> (among possibly others). I follow this trend with a correction on
> the folder versus prefix. That's why device/types.h.
> 
> $ git diff $A..$B --diff-filter=A --name-only -- include/ | grep _types.h
> 
> In v6.19:
> include/linux/fs/super_types.h
> include/linux/irq_work_types.h
> include/linux/ns/ns_common_types.h
> include/linux/ns/nstree_types.h
> include/linux/rseq_types.h

Please no, let's keep things simple.  I only split up device.h because
it made sense for the class/bus stuff to be out of it.  Let's not just
try to make things even more fine-grained for no good reason (speed of
builds, size, etc.), which I do not see justified here at all.

thanks,

greg k-h