Hi Vaibhav,

On 4/25/2012 7:48 AM, Hiremath, Vaibhav wrote:
On Wed, Apr 25, 2012 at 06:33:26, Paul Walmsley wrote:
Hello Vaibhav, Afzal, Vaibhav,

On Tue, 3 Apr 2012, Vaibhav Hiremath wrote:

AM33XX clock implementation is different than any existing OMAP
family of devices. Although DPLL module is similar to OMAP4
device, but the usage is very much different than OMAP4.
AM33XX has different peripheral set and each module gets
integrated to the clock framework differently than OMAP
family of devices.

This patch adds full Clock tree data for AM33XX family
of devices and also integrates it into existing OMAP framework.

What do you think about the possibility of removing all of the leaf clocks
that have AM33XX_MODULEMODE_SWCTRL as their .enable_bit, assuming there
are no .fixed_div or .clksel* fields associated with the clocks?

In theory, I don't think they are needed.  The drivers should be using
runtime PM, and that should enable and disable the module via the hwmod
code, rather than the clock code.

Of course some clocks would still be needed for the main_clk fields for
the hwmods, but the hwmods should be able to use the leaf clock's parent
clocks for that.

That would save quite a few lines of data.  And I think BenoƮt is planning
to do that for OMAP4+.

What do you think?


Yes, theoretically it is possible to do it. But it will also break some of
the existing things, like,

1. DebugFS clock interface

I believe, with this change, you will not have all the leaf nodes as part of 
clock tree, so they will not be populated in /debug/clock/

2. Enable and disable of the module is one part, but what about, changing
    the rate of the clock (followparent_recalc)?
    With the proper and complete clock tree, you can traverse the clock and
    driver code doesn't need to know about parent.
    Driver can simply call clk_set_rate() on leaf clock, and clock tree will
    handle it.

If at all we take this path, we have to build the clk node runtime
(on-the-fly), AND/OR add new pm_runtime_set_rate() api.

Not at all. You just have to get the fck of that hwmod and use the clock API.

Are you available on IRC chat anytime? We can discuss on this and align
I am available on linux-omap irc channel (with the name = "hvaibhav")

That will not change anything, the point is that MODULEMODE_SWCTRL is uses for module control, not for clock directly, and that's why it is handled by the hwmod.

That will just replace the main_clk from the hwmod with the parent of the current modulemode nodes. Only the enable/disable part will be handled, if that node used to have a div, then the parent will handle that.

Today this module mode clock node is just a duplication of the hwmod node. By removing it, you will reduce the size of the data and have a much mode accurate representation of the reality.

Using the clock tree to handle these nodes was a hack we had to do because the hwmod fmwk was not ready when OMAP4 was introduced and because most drivers were not using pm_runtime.

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