Re: [PATCH] AM35xx: disable checking for reserved feature bits

[Kevin Hilman <khilman@ti.com>]

Tony Lindgren <tony@atomide.com> writes:

[...]

>> This "feature" selection mechanism is clearly not scaling to newer SoCs.
>> While this patch works around the problem, IMO, we need a more scalable
>> solution.
>
> Agreed.
>  
>> For features like IVA and ISP (and SGX) which are acutally IP blocks on
>> the SoC, not "features"  per-se, what we really need to be doing is
>> checking for the presence of the IP block, not checking a bit in a
>> register that's not consistent across various SoCs.
>> 
>> We already have all the knowledge about whether the IP blocks are
>> present in the SoC-specific hwmod data.  So checking for the "feature"
>> of a specific IP block should instead be done using an
>> omap_hwmod_lookup().
>> 
>> However, there's a bit of a snag because this "feature" detection is
>> currently done before the hwmods are registered.
>> 
>> As a quick-and-dirty proof of concept, the patch/hack below moves the
>> feature checking after the hwmod init (omap3 only currently) and uses
>> omap_hwmod_lookup() to check whether a given IP block exists.
>> 
>> I only did a quick test on one OMAP3 platform (3430/n900) and it seems
>> to work.    The init order changes need some more thought, as I didn't
>> fully validate whether the feature detection can be safely moved later
>> for all platforms.
>> 
>> This is just to show the direction we should be taking this SoC
>> detection for newer SoCs.
>
> This should be coordinated with the splitting of feature detection
> as posted by Vaibhave in thread "[RFC PATCH] arm:omap: cleanup & split
> omap2/3/4_check_revision function" thread.

Vaibhav,

Feel free to take my proposed patch and develop it further and include
it in your rework of the SoC/feature detection.

Kevin