Messages in this thread | | | Date | Wed, 29 Jun 2016 21:59:56 +0800 | From | Dong Aisheng <> | Subject | Re: [RESEND PATCH 4/8] clk: core: support clocks which requires parents on (part 2) |
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Hi Mike,
On Fri, Jun 24, 2016 at 04:52:59PM -0700, Michael Turquette wrote: > Hi Dong, > > Quoting Dong Aisheng (2016-04-20 02:34:36) > > On Freescale i.MX7D platform, all clocks operations, including > > enable/disable, rate change and re-parent, requires its parent clock on. > > Current clock core can not support it well. > > This patch adding flag CLK_OPS_PARENT_ON to handle this special case in > > clock core that enable its parent clock firstly for each operation and > > disable it later after operation complete. > > > > The patch part 2 fixes set clock rate and set parent while its parent > > is off. The most special case is for set_parent() operation which requires > > all parents including both old and new one to be enabled at the same time > > during the operation. > > > > Cc: Michael Turquette <mturquette@baylibre.com> > > Cc: Stephen Boyd <sboyd@codeaurora.org> > > Cc: Shawn Guo <shawnguo@kernel.org> > > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com> > > --- > > drivers/clk/clk.c | 45 ++++++++++++++++++++++++++++----------------- > > 1 file changed, 28 insertions(+), 17 deletions(-) > > > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > > index 1f054d1a..d6cef61 100644 > > --- a/drivers/clk/clk.c > > +++ b/drivers/clk/clk.c > > @@ -1174,7 +1174,7 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core, > > struct clk_core *old_parent = core->parent; > > > > /* > > - * Migrate prepare state between parents and prevent race with > > + * 1. Migrate prepare state between parents and prevent race with > > * clk_enable(). > > * > > * If the clock is not prepared, then a race with > > @@ -1189,13 +1189,16 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core, > > * hardware and software states. > > * > > * See also: Comment for clk_set_parent() below. > > + * > > + * 2. enable parent clocks for CLK_OPS_PARENT_ON clock > > */ > > - if (core->prepare_count) { > > - clk_core_prepare(parent); > > - flags = clk_enable_lock(); > > - clk_core_enable(parent); > > - clk_core_enable(core); > > - clk_enable_unlock(flags); > > + if (core->prepare_count || core->flags & CLK_OPS_PARENT_ON) { > > + clk_core_prepare_enable(parent); > > + if (core->prepare_count) > > + clk_core_enable_lock(core); > > + else > > + clk_core_prepare_enable(old_parent); > > It took me a few seconds to figure out what I was looking at. The > set_parent stuff is tricky enough already ... I think we should keep the > state machine logic very simple. How about: > > /* enable old_parent & parent if CLK_OPS_PARENT_ENABLE is set */ > if (core->flags & CLK_OPS_PARENT_ENABLE) { > clk_core_prepare_enable(old_parent); > clk_core_prepare_enable(parent); > } > > /* migrate prepare count if > 0 */ > if (core->prepare_count) { > clk_core_prepare_enable(parent); > clk_core_enable_lock(core); > } >
Great suggestion! That looks much clearer. Will update it in V2.
Thanks
Regards Dong Aisheng
> > + > > } > > > > /* update the clk tree topology */ > > @@ -1210,18 +1213,16 @@ static void __clk_set_parent_after(struct clk_core *core, > > struct clk_core *parent, > > struct clk_core *old_parent) > > { > > - unsigned long flags; > > - > > /* > > * Finish the migration of prepare state and undo the changes done > > * for preventing a race with clk_enable(). > > */ > > - if (core->prepare_count) { > > - flags = clk_enable_lock(); > > - clk_core_disable(core); > > - clk_core_disable(old_parent); > > - clk_enable_unlock(flags); > > - clk_core_unprepare(old_parent); > > + if (core->prepare_count || core->flags & CLK_OPS_PARENT_ON) { > > + clk_core_disable_unprepare(old_parent); > > + if (core->prepare_count) > > + clk_core_disable_lock(core); > > + else > > + clk_core_disable_unprepare(parent); > > Similarly, a more readable solution is: > > /* > * Finish the migration of prepare state and undo the changes done > * for preventing a race with clk_enable(). > */ > if (core->prepare_count) { > clk_core_disable_lock(core); > clk_core_disable_unprepare(old_parent); > > /* re-balance ref counting if CLK_OPS_PARENT_ENABLE is set */ > if (core->flags & CLK_OPS_PARENT_ENABLE) { > clk_core_disable_unprepare(parent); > clk_core_disable_unprepare(old_parent); > } > > > } > > } > > > > @@ -1468,13 +1469,17 @@ static void clk_change_rate(struct clk_core *core) > > unsigned long best_parent_rate = 0; > > bool skip_set_rate = false; > > struct clk_core *old_parent; > > + struct clk_core *parent = NULL; > > > > old_rate = core->rate; > > > > - if (core->new_parent) > > + if (core->new_parent) { > > + parent = core->new_parent; > > best_parent_rate = core->new_parent->rate; > > - else if (core->parent) > > + } else if (core->parent) { > > + parent = core->parent; > > best_parent_rate = core->parent->rate; > > + } > > > > if (core->flags & CLK_SET_RATE_UNGATE) { > > unsigned long flags; > > @@ -1504,6 +1509,9 @@ static void clk_change_rate(struct clk_core *core) > > > > trace_clk_set_rate(core, core->new_rate); > > > > + if (core->flags & CLK_OPS_PARENT_ON) > > + clk_core_prepare_enable(parent); > > + > > if (!skip_set_rate && core->ops->set_rate) > > core->ops->set_rate(core->hw, core->new_rate, best_parent_rate); > > > > @@ -1520,6 +1528,9 @@ static void clk_change_rate(struct clk_core *core) > > clk_core_unprepare(core); > > } > > > > + if (core->flags & CLK_OPS_PARENT_ON) > > + clk_core_disable_unprepare(parent); > > + > > This part looks good to me. > > Regards, > Mike > > > if (core->notifier_count && old_rate != core->rate) > > __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate); > > > > -- > > 1.9.1 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-clk" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
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