Re: [PATCH 01/13] clk: add new flag CLK_ROUNDING_FW_MANAGED

[Brian Masney <bmasney@redhat.com>]

On Fri, Feb 27, 2026 at 12:00:55PM +0000, Biju Das wrote:
> > -----Original Message-----
> > From: linux-arm-kernel <linux-arm-kernel-bounces@lists.infradead.org> On Behalf Of Brian Masney
> > Sent: 26 February 2026 18:17
> > Subject: [PATCH 01/13] clk: add new flag CLK_ROUNDING_FW_MANAGED
> > 
> > There are some clocks where the rounding is managed by the hardware, and the determine_rate() clk ops
> > is just a noop that simply returns 0. Add a new flag for these type of clocks, and update the clk core
> > so that the
> > determine_rate() clk op is not required when this flag is set.
> > 
> > Signed-off-by: Brian Masney <bmasney@redhat.com>
> > 
[snip]
> >  drivers/clk/clk.c            | 24 +++++++++++++++++++++---
> >  include/linux/clk-provider.h |  2 ++
> >  2 files changed, 23 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index
> > fd418dc988b1c60c49e3ac9c0c44aa132dd5da28..0a522a0817411c7f7c6e9cffd6f024e672a331a8 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -1557,6 +1557,20 @@ static int __init clk_disable_unused(void)  }
> > late_initcall_sync(clk_disable_unused);
> > 
> > +/**
> > + * clk_is_rounding_fw_managed - Check to see if clk rounding is handled
> > +by the
> > + * firmware.
> > + * @core: the clk to check
> > + *
> > + * Clks that have this flag enabled do not need to have a
> > +determine_rate() op
> > + * set, and will always return success for any rounding operation since
> > +the
> > + * firmware will deal with the rounding.
> > + */
> > +static inline bool clk_is_rounding_fw_managed(struct clk_core *core) {
> > +	return core->flags & CLK_ROUNDING_FW_MANAGED; }
> > +
> >  static int clk_core_determine_round_nolock(struct clk_core *core,
> >  					   struct clk_rate_request *req)
> >  {
> > @@ -1589,6 +1603,8 @@ static int clk_core_determine_round_nolock(struct clk_core *core,
> >  		req->rate = core->rate;
> >  	} else if (core->ops->determine_rate) {
> >  		return core->ops->determine_rate(core->hw, req);
> > +	} else if (clk_is_rounding_fw_managed(core)) {
> > +		return 0;
> >  	} else {
> >  		return -EINVAL;
> >  	}
> > @@ -1673,7 +1689,7 @@ EXPORT_SYMBOL_GPL(clk_hw_forward_rate_request);
> > 
> >  static bool clk_core_can_round(struct clk_core * const core)  {
> > -	return core->ops->determine_rate;
> > +	return core->ops->determine_rate || clk_is_rounding_fw_managed(core);
> >  }
> > 
> >  static int clk_core_round_rate_nolock(struct clk_core *core, @@ -3528,6 +3544,7 @@ static const
> > struct {
> >  	ENTRY(CLK_IS_CRITICAL),
> >  	ENTRY(CLK_OPS_PARENT_ENABLE),
> >  	ENTRY(CLK_DUTY_CYCLE_PARENT),
> > +	ENTRY(CLK_ROUNDING_FW_MANAGED),
> >  #undef ENTRY
> >  };
> > 
> > @@ -3906,7 +3923,7 @@ static int __clk_core_init(struct clk_core *core)
> > 
> >  	/* check that clk_ops are sane.  See Documentation/driver-api/clk.rst */
> >  	if (core->ops->set_rate && !core->ops->determine_rate &&
> > -	      core->ops->recalc_rate) {
> > +	      core->ops->recalc_rate && !clk_is_rounding_fw_managed(core)) {
> >  		pr_err("%s: %s must implement .determine_rate in addition to .recalc_rate\n",
> >  		       __func__, core->name);
> >  		ret = -EINVAL;
> > @@ -3920,7 +3937,8 @@ static int __clk_core_init(struct clk_core *core)
> >  		goto out;
> >  	}
> > 
> > -	if (core->ops->set_parent && !core->ops->determine_rate) {
> > +	if (core->ops->set_parent && !core->ops->determine_rate &&
> > +	    !clk_is_rounding_fw_managed(core)) {
> 
> >  		pr_err("%s: %s must implement .set_parent & .determine_rate\n",
> >  			__func__, core->name);
> >  		ret = -EINVAL;
> 
> 
> After applying patch#11, I get a message as you removed .determine_rate, Also it breaks display.
> 
> [    0.096414] __clk_core_init: .pll5_foutpostdiv must implement .round_rate or .determine_rate in addition to .recalc_rate

Thanks for testing. This happens because rzg2l_cpg_pll_clk_register()
doesn't have the new flag set. I'll fix this, and go through all of the
others again just to make sure I don't miss any others.

Brian