[PATCH v5 0/5] clk: implement remuxing during set_rate

Mike Turquette
2013-06-21T17:04:07Z

Quoting James Hogan (2013-06-13 09:05:57)
> This patchset adds support for automatic selection of the best parent
> for a clock mux, i.e. the one which can provide the closest clock rate
> to that requested. It can be disabled by a new CLK_SET_RATE_NO_REPARENT
> flag (which is set for all uses of clk_register_mux().
>
> This works by way of adding a new op, determine_rate, similar to
> round_rate but with an extra parameter to allow the clock driver to
> optionally select a different parent clock. This is used in
> clk_calc_new_rates to decide whether to initiate a set_parent operation.

Hi James,

I'm going to hold off on this one for 3.11. I'll revisit it after the
next merge window.

Regards,
Mike

>
> Changes in v5:
>
> * Rebased on latest clk-next ("clk: tegra: Use common of_clk_init
> function")
> * Updated clock hardware characteristics table in documentation.
>
> Changes in v4:
>
> * rebased on clk-next ("clk: sun5i: Add compatibles for Allwinner A13").
> * replace __clk_set_parent_no_recalc with __clk_set_parent.
> * never pass NULL to determine_rate's best_parent_clk parameter, and
> slight refactor of __clk_round_rate to use local copy of clk->parent.
> * a few new comments around use of clk::new_child.
> * new patch (patch 2) split out of patch 3 to avoid having to declare
> static __clk_set_parent() at the top of clk.c, and to ease readability
> of patch 3.
>
> Changes in v3:
>
> * rebased on v3.10-rc1.
> * remove double underscore prefix from clk_get_parent_by_index()
> * store new_parent_index in struct clk too (calculated from
> clk_fetch_parent_index, and passed through __clk_set_parent_no_recalc
> to __clk_set_parent).
> * allow determine_rate to satisfy recalc_rate check in __clk_init.
> * rename/invert CLK_SET_RATE_REMUX to CLK_SET_RATE_NO_REPARENT and move
> to patch 3.
> * patch 3: add CLK_SET_RATE_NO_REPARENT flag to all callers of
> clk_register_mux. If you don't mind your clocks being reparented in
> response to set_rate please let me know and I'll drop the relevant
> portion of the patch.
>
> Changes in v2:
>
> I've moved the mux determine_rate implementation into a core helper, but
> I haven't pushed it fully into the core, as I think it just wouldn't
> work correctly for more complex clocks, e.g. if you (theoretically) had
> a combined mux and divide, you'd want to intercept the determine_rate
> and ask for a larger rate from the parent clocks, then return the
> divided rate. This should be possible by wrapping the mux determine_rate
> helper.
>
> Patch 1 still exports the __clk_get_parent_by_index as it seems like it
> might be a useful thing for clock implementations to have access to if
> they ever wanted to do something more fancy with changing clock parents.
>
> I haven't made any attempt to implement the atomic set_parent+set_rate
> as I don't have hardware that could take proper advantage of it, but it
> shouldn't be too difficult for others to implement if they wanted since
> they're fairly close to one another (in clk_change_rate()).
>
> * switched to using new determine_rate op rather than adding an argument
> to round_rate.
> * moved mux implementation into a single helper which should be usable
> from more complex clocks which can mux.
> * rewrite main implementation so that no changes are made until after
> the PRE notifications have been sent, and in a way that should ensure
> correct notifications without duplicates, and I think should be safe
> in the event of a notification failing.
> * various tidy ups and fixes.
>
> James Hogan (5):
> clk: abstract parent cache
> clk: move some parent related functions upwards
> clk: add support for clock reparent on set_rate
> clk: add CLK_SET_RATE_NO_REPARENT flag
> clk: clk-mux: implement remuxing on set_rate
>
> Documentation/clk.txt | 46 ++--
> arch/arm/mach-imx/clk.h | 5 +-
> drivers/clk/clk-mux.c | 1 +
> drivers/clk/clk.c | 420 ++++++++++++++++++++++-------------
> drivers/clk/mmp/clk-mmp2.c | 39 ++--
> drivers/clk/mmp/clk-pxa168.c | 40 ++--
> drivers/clk/mmp/clk-pxa910.c | 31 ++-
> drivers/clk/mxs/clk.h | 4 +-
> drivers/clk/samsung/clk.h | 2 +-
> drivers/clk/spear/spear1310_clock.c | 179 ++++++++-------
> drivers/clk/spear/spear1340_clock.c | 97 ++++----
> drivers/clk/spear/spear3xx_clock.c | 57 +++--
> drivers/clk/spear/spear6xx_clock.c | 35 +--
> drivers/clk/sunxi/clk-sunxi.c | 3 +-
> drivers/clk/tegra/clk-tegra114.c | 36 ++-
> drivers/clk/tegra/clk-tegra20.c | 6 +-
> drivers/clk/tegra/clk-tegra30.c | 33 ++-
> drivers/clk/versatile/clk-vexpress.c | 4 +-
> include/linux/clk-private.h | 3 +
> include/linux/clk-provider.h | 12 +
> 20 files changed, 638 insertions(+), 415 deletions(-)
>
> --
> 1.8.1.2