Premi, Sanjeev had written, on 10/06/2009 03:52 AM, the following:
+ {0, 0, 0},
+ /*OPP1*/
+ {S125M, VDD1_OPP1, 0x1E},
+ /*OPP2*/
+ {S250M, VDD1_OPP2, 0x26},
+ /*OPP3*/
+ {S500M, VDD1_OPP3, 0x30},
+ /*OPP4*/
+ {S550M, VDD1_OPP4, 0x36},
+ /*OPP5*/
+ {S600M, VDD1_OPP5, 0x3C},
+};
For those involved,
if we wanted to convert omap3_mpu_table[] into
*omap3_mpu_table so that
we dynamically initialize it based on cpu type - what
would be the
recommendations?
Nishanth,
Good idea!
As a table, previous patch enables it (not as intent, but due to
syntax):
> +/* struct omap_opp_table - View OPP table as an object
> + * @min: Minimum OPP id
> + * @max: Maximim OPP id
> + * @opps: Pointer to array defining the OPPs.
> + *
> + * An OPP table has varied length. Knowing minimum
and maximum
> + * OPP ids allow easy traversal.
> + */
> +struct omap_opp_table {
> + u8 min;
> + u8 max;
> + struct omap_opp* opps;
> +};
But now, I think it would be good to have an API that can fill an
opp_table:
int add_opp_definition(u8 id, u32 freq, u16 vsel);
...and, if an array is preferred, length can be set as:
int set_opp_table_length (u8 max);
I'm all for dynamic OPP setting, but not as an array. A
list should
probably be used.
Won't a list implementation cause more than necessary
overhead? I agree
that something like set_opp_table_length probably might be
redundant in
that case.
I'm aligned with Nishanth. I think a static table with the
possibility to disable some entry is good enough to deal with
most of the OPPs we have on OMAP3 and we will have to handle on OMAP4.
OPPs are defined during silicon characterization, and should
not be changed dynamically (in theory).
[sp] The intent of 'dynamic' is not with respect to changing the
OPPs but manitaining OPPs in an array or a list.
This is to take care of possibility that an OPP is not
applicable for specific devices. E.g. OPP5 was earlier
considered 'overdrive'; and the code had a small 'hack'
to prevent this OPP being used during cpufreq.
Marking the OPP 'disabled/invalid' in the table would have
been a better solution.
In a 'list' implementation, the node corresponding to such
OPPs can be removed from the 'active' list.
Couple of opinions on why a list with disabled/invalid marker might not
make sense as a grand unified OPP table:
a) it is no better than a list implementation
b) it is a waste of memory.
c) search Algo overheads
Recommendation a.k.a hybrid approach:
* Each silicon has it's own static OPP table
* Each table has a invalid marker which is disabled for silicon variants
which dont need specific OPPs
* OPPs table be stored in a hash table a.k.a how do we optimize search
for OPP params?
--
Regards,
Nishanth Menon
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