[PATCH v5 02/14] ARM: OMAP2+: gpmc: Adapt to HWMOD

[Mohammed, Afzal]

Hi Tony,

On Wed, Jun 13, 2012 at 17:32:09, Tony Lindgren wrote:
> * Mohammed, Afzal <afzal at ti.com> [120612 22:24]:
> > Hi Jon,
> > 
> > On Tue, Jun 12, 2012 at 23:10:01, Hunter, Jon wrote:

> > > Right but potentially, this could be done by the driver.
> > 
> > I do not think it is practically possible. Please see timing calculations
> > in arch/arm/mach-omap2/gpmc-*, the way it is done for different
> > peripherals are different, and we cannot expect gpmc driver to do those as
> > that would require gpmc driver being aware of type of peripheral connected.
> > 
> > And all those gpmc-* timing calculation needs to be done before driver
> > is ready, they rely on functions like gpmc_get_fclk_rate(), which in turn
> > requires the clk rate to be available before driver is probed.
> 
> Yeah I also think the GPMC code should handle the L3 timings, and dynamically
> calculate them for DVFS when L3 frequency changes. Does the GPMC have enough
> information now to do that?

Do you mean that gpmc driver should have the capability to calculate peripheral
timings at runtime based on frequency ?, I am not sure how this can be handled
by gpmc driver as calculation for different peripherals are done in different
way, requiring gpmc driver to know about connected peripheral, that would imply
that gpmc driver would not be peripheral agnostic.

Or else some sort of a callback to be used ?

Out of the 20,14 are depending on bootloader, both omap3evm & beagle has been
converted to utilize runtime calculation, but for other 12 boards, first
we need to get values used by bootloader (those include peripherals that doesn't
have gpmc-* helpers), then derive it based on expression, after that only, we
will have information to achieve it and those are the ones that I do not
have access to.
 
Regards
Afzal

> 
> Additionally GPMC should add constraints to DVFS if not enough data is know
> to scale L3.
> 
> Tony
>