On Tue, Apr 09, 2013 at 01:45:44PM +0200, Wim Van Sebroeck wrote: > Hi Guenter, > > > I was waiting for feedback from Wim, who submitted a similar driver, about his > > thoughts. Key question is how to reserve access to the shared resource - either > > through an exported function in the mfd driver requesting a mutex, or through > > request_muxed_region(). I am going back and forth myself on which one is better. > > > > Maybe it does not really matter, but using a function has the slight advantage > > that it auto-loads and locks the mfd module while one of its client modules > > is loaded. If we use request_muxed_region, that is not the case and the client > > module must use another means to request and lock the mfd module. > > > > Maybe you have an opinion ? > > This is indeed the main issue that has to be solved. Both options will work. > I like the auto-load and lock, but I need to look at the request_muxed_region > code again first before I can see what the possible drawbacks are :-). > One drawback of using request_muxed_region is that it needs a return value from superio_enter. Also, it needs some code in the client driver init function to ensure that the mfd driver gets loaded, and possibly a call to __module_get() in the client driver probe function to keep the mfd driver loaded. winbond_superio_enter() would not need a return value and could use devm_request_region. We could also consider allocating the hwmon memory space in the mfd driver and pass it as resource to the client drivers, which would remove a few more lines of code from those. Overall I am slightly in favor of using an exported function. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
