Re: [PATCH v2 RESEND] pwm: Add CLPS711X PWM support

["Alexander Shiyan" <shc_work@mail.ru>]

Суббота,  1 марта 2014, 12:40 +01:00 от Arnd Bergmann <arnd@arndb.de>:
> On Saturday 01 March 2014, Alexander Shiyan wrote:
> > I want to elaborate on the current CLPS711X lineup:
> > PS7110  - EOL October 30, 2001
> > PS7111  - EOL October 30, 2001
> > EP7209  - EOL April 25, 2003
> > EP7211  - EOL April 25, 2003
> > EP7212  - EOL April 25, 2003
> > CS89712 - EOL August 15, 2005
> > EP7309  - Production
> > EP7311  - Production
> > EP7312  - Production
> 
> Thanks for the list. I wonder if there is a good place to keep this in the
> kernel source for reference.
> 
> > So at the moment, and long enough, produced only three models of CPUs.
> > I am sure that the hardware with old CPUs will not be able to use the
> > new kernel due to memory limitations, low CPU frequency, etc.
> > 
> > My suggestion is to always use a compatibility string for platform entirely,
> > ie "cirrus,clps711x-$UNIT", otherwise it may result in misleading.
> 
> From your list, it's pretty clear that there won't be any new chips named
> PS711x for x > 1, so using that string is not ambiguous. That is good
> to know. It's also the oldest chip in the family, so naming things after that
> is consistent.
> 
> > In any case, I would like to hear the final decision on this issue,
> > since there are several drivers already using this scheme and some drivers
> > awaiting applying into the kernel.
> > I do not insist on its position, but just want to clarify to make changes
> > to existing drivers and use the approved compatibility string in the future.
> > At the current stage, these changes will not lead to anything terrible.
> 
> How about we keep using the cirrus,clps711x as the string that drivers
> match against, but change the DT representation to always list the specific
> model in addition? That way we are prepared to handle quirks if we need to,
> but you don't have to change the binding in incompatible ways.
> 
> This means you should list e.g.
> 
> 	compatible = "cirrus,ep7309-pwm", "cirrus,clps711x-pwm";
> 
> or 
> 
> 	compatible = "cirrus,clps7110-pwm", "cirrus,clps711x-pwm";
> 
> depending on the model. For units that were introduced in a later
> model, I would recommend to use the first model that had it rather
> than the original clps711x that didn't, like
> 
> 	compatible = "cirrus,ep7311-kitchensink", "cirrus-ep7211-kitchensink";
> 
> For bindings that are already reviewed and merged, I wouldn't change
> them any more even if they inaccurately list clps711x for units that
> were not present in clps7111, but for new ones I'd prefer to follow
> the common practice to your best knowledge.

Excellent, let's do so. I will prepare a patch that will change compatibility
strings for examples in the current bindings documents.
For this driver (PWM), I just send a third version.

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