On Fri, Mar 24, 2017 at 05:11:25PM +0100, Bartlomiej Zolnierkiewicz wrote: > On Friday, March 24, 2017 06:46:00 PM Krzysztof Kozlowski wrote: > > I really do not like global or file-scope variables. I do not like > > drivers using them. Actually I hate them. > > > > From time to time I encounter a driver which was designed with that > > approach - static fields and hidden assumption that there will be only > > one instance. Usually that assumption is really hidden... > > > > ... and then it happens that I want to use two instances which of course > > fails. > > > > This code serves as a clear documentation for this assumption - only one > > instance is allowed. You can look at it as a self-documenting > > requirement. > > For me it looks as needless case of defensive programming and when > I see the code like this it always raises questions about the real > intentions of the code. I find it puzzling and not helpful. I do not understand what might be puzzling about check for static file-scope value. It is of course subjective, but for me that looks pretty self-explanatory. > > > And I think the probe might be called twice, for example in case of > > mistake in DTB. > > Even if this is possible resource allocation code in the driver will > take take care of handling it just fine, Indeed, the devm_ioremap_resource() solves the case. I can drop the check then. Best regards, Krzysztof
