Re: [PATCH 1/3] PM / Domains: Allow overriding the ->xlate() callback

[Jon Hunter <jonathanh@nvidia.com>]

On 15/03/17 13:36, Thierry Reding wrote:
> * PGP Signed by an unknown key
> 
> On Tue, Mar 14, 2017 at 08:34:01PM +0000, Jon Hunter wrote:
>>
>> On 14/03/17 19:15, Thierry Reding wrote:
>>> From: Thierry Reding <treding@nvidia.com>
>>>
>>> Allow generic power domain providers to override the ->xlate() callback
>>> in case the default genpd_xlate_onecell() translation callback is not
>>> good enough.
>>>
>>> One potential use-case for this is to allow generic power domains to be
>>> specified by an ID rather than an index.
>>
>> Are you sure this is necessary, because I recall that the genpd core
>> does allow for holes in the domain array (which is what we have). See
>> commit 609bed67bd8f ('PM / Domains: Allow holes in genpd_data.domains
>> array').
> 
> I suppose we could use that, but it feels like the wrong solution to me.
> Why would we want to deal with holes in the array when we can simply do
> all the required work at probe time and add only the existing domains in
> any particular SoC.
> 
> For example on Tegra186 we've got a maximum ID of 43, so we'd need to
> allocate 44 pointers, but we only use 17 of those IDs. People usually
> reply to that that newer SoCs come with enough memory to make this
> waste irrelevant. I don't buy that. Why should we waste memory if it
> can be easily avoided?

I was wondering how many holes we have. That seems a bit excessive and
so I would agree it is a waste.

Cheers
Jon

-- 
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