Hi Benoit, On Wed, May 29, 2013 at 14:09:18, Cousson, Benoit wrote: > On 05/29/2013 10:06 AM, Mohammed, Afzal wrote: > > On Wed, May 29, 2013 at 03:35:10, Stephen Warren wrote: > >> On 05/28/2013 03:25 PM, Jon Hunter wrote: > >>> If you are adding more compatibility strings, then this implies that the > >>> AM43x timers are not 100% compatible with any other device listed (such > >>> as am335x or any omap device). That's fine but you should state that in > >>> the changelog. If the AM43x timer registers are 100% compatible with > >>> existing devices you should not add these. > >> > >> I'm not sure that's true; .dts files should always include a compatible > >> value that describes the most specific model of the HW, plus any > >> baseline compatible value that the HW is compatible with. This allows > >> any required quirks/fixes/... to be applied for the specific HW model > >> later even if nobody knows right now they'll be needed. Hence, defining > >> new compatible values doesn't necessarily mean incompatible HW. > > > > Stephen took words out of my finger ;) > > > > Some explanations,I don;t > > > > 1. first compatible should be exact device [A], followed by compatible > > model (if one) > > 2. Minor effort in getting DT right the first time may help prevent > > difficult effort later modifying it (if a necessity comes), considering > > the fact that DT sources has to move out of Kernel at some point of > > time. And DT is not supposed to be modified, which may cause difficulty > > for the users (I had been a minor victim of this during rebase). > > > > As we both were in GPMC land earlier, an example, > > > > If my memory is right, GPMC IP in am335x is rev 6, and IP has 8 chip > > select, but one is not pinned out. Now assume that same IP is integrated > > in another SoC (probably OMAP4 has rev 6). Here if we use same compatible > > for both, driver cannot handle it properly (w/o knowledge about platform). > > But if exact compatible is mentioned, without modifying DT (which should > > be considered as a firmware) just by modifying Kernel, deciding based on > > compatible would help achieve what is required. > > That's true for the DTS itself, but here your are changing the binding > documentation which is supposed to reflect the driver "interface" in the > Device Tree model description. > > Since the driver does not support any new compatible string, you should > not update the binding. I have a different opinion: Binding documentation is to be considered an entity that is not a part of the Kernel, but currently is a part of the Kernel for want of a better place. And binding is to be considered OS agnostic being ignorant of any piece of software (driver here). Binding has the authority to allow its usage in DT sources. > The driver and the binding will have to be changed the day you will have > to update the driver to handle a bug / feature specific to that revision > (ti,am4372-timer). > > Since this series does not seems to update the driver, you should not > update the bindings. I believe that updating binding is a prerequisite for making a new DTS change, hence binding was updated first, then DTS. Regards Afzal ��.n��������+%������w��{.n�����{����*jg��������ݢj����G�������j:+v���w�m������w�������h�����٥