Commit 49e62e0d authored by Maxime Ripard's avatar Maxime Ripard Committed by Stephen Boyd
Browse files

clk: Add trace events for rate requests 



It is currently fairly difficult to follow what clk_rate_request are
issued, and how they have been modified once done.

Indeed, there's multiple paths that can be taken, some functions are
recursive and will just forward the request to its parent, etc.

Adding a lot of debug prints is just not very convenient, so let's add
trace events for the clock requests, one before they are submitted and
one after they are returned.

That way we can simply toggle the tracing on without modifying the
kernel code and without affecting performances or the kernel logs too
much.

Reviewed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarMaxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20221018-clk-rate-request-tracing-v2-2-5170b363c413@cerno.tech


Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
parent ef13f8b6

drivers/clk/clk.c

+31 −0
Original line number Original line Diff line number Diff line
@@ -603,10 +603,15 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw, 
			}

			}





			clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate);

			clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate);



			trace_clk_rate_request_start(&parent_req);



			ret = clk_core_round_rate_nolock(parent, &parent_req);

			ret = clk_core_round_rate_nolock(parent, &parent_req);

			if (ret)

			if (ret)

				return ret;

				return ret;





			trace_clk_rate_request_done(&parent_req);



			best = parent_req.rate;

			best = parent_req.rate;

		} else if (parent) {

		} else if (parent) {

			best = clk_core_get_rate_nolock(parent);

			best = clk_core_get_rate_nolock(parent);
@@ -630,10 +635,15 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw, 
			struct clk_rate_request parent_req;

			struct clk_rate_request parent_req;





			clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate);

			clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate);



			trace_clk_rate_request_start(&parent_req);



			ret = clk_core_round_rate_nolock(parent, &parent_req);

			ret = clk_core_round_rate_nolock(parent, &parent_req);

			if (ret)

			if (ret)

				continue;

				continue;





			trace_clk_rate_request_done(&parent_req);



			parent_rate = parent_req.rate;

			parent_rate = parent_req.rate;

		} else {

		} else {

			parent_rate = clk_core_get_rate_nolock(parent);

			parent_rate = clk_core_get_rate_nolock(parent);
@@ -1547,10 +1557,15 @@ static int clk_core_round_rate_nolock(struct clk_core *core, 
		struct clk_rate_request parent_req;

		struct clk_rate_request parent_req;





		clk_core_forward_rate_req(core, req, core->parent, &parent_req, req->rate);

		clk_core_forward_rate_req(core, req, core->parent, &parent_req, req->rate);



		trace_clk_rate_request_start(&parent_req);



		ret = clk_core_round_rate_nolock(core->parent, &parent_req);

		ret = clk_core_round_rate_nolock(core->parent, &parent_req);

		if (ret)

		if (ret)

			return ret;

			return ret;





		trace_clk_rate_request_done(&parent_req);



		req->best_parent_rate = parent_req.rate;

		req->best_parent_rate = parent_req.rate;

		req->rate = parent_req.rate;

		req->rate = parent_req.rate;
@@ -1601,10 +1616,14 @@ unsigned long clk_hw_round_rate(struct clk_hw *hw, unsigned long rate) 




	clk_core_init_rate_req(hw->core, &req, rate);

	clk_core_init_rate_req(hw->core, &req, rate);





	trace_clk_rate_request_start(&req);



	ret = clk_core_round_rate_nolock(hw->core, &req);

	ret = clk_core_round_rate_nolock(hw->core, &req);

	if (ret)

	if (ret)

		return 0;

		return 0;





	trace_clk_rate_request_done(&req);



	return req.rate;

	return req.rate;

}

}

EXPORT_SYMBOL_GPL(clk_hw_round_rate);

EXPORT_SYMBOL_GPL(clk_hw_round_rate);
@@ -1633,8 +1652,12 @@ long clk_round_rate(struct clk *clk, unsigned long rate) 




	clk_core_init_rate_req(clk->core, &req, rate);

	clk_core_init_rate_req(clk->core, &req, rate);





	trace_clk_rate_request_start(&req);



	ret = clk_core_round_rate_nolock(clk->core, &req);

	ret = clk_core_round_rate_nolock(clk->core, &req);





	trace_clk_rate_request_done(&req);



	if (clk->exclusive_count)

	if (clk->exclusive_count)

		clk_core_rate_protect(clk->core);

		clk_core_rate_protect(clk->core);
@@ -2126,10 +2149,14 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *core, 




		clk_core_init_rate_req(core, &req, rate);

		clk_core_init_rate_req(core, &req, rate);





		trace_clk_rate_request_start(&req);



		ret = clk_core_determine_round_nolock(core, &req);

		ret = clk_core_determine_round_nolock(core, &req);

		if (ret < 0)

		if (ret < 0)

			return NULL;

			return NULL;





		trace_clk_rate_request_done(&req);



		best_parent_rate = req.best_parent_rate;

		best_parent_rate = req.best_parent_rate;

		new_rate = req.rate;

		new_rate = req.rate;

		parent = req.best_parent_hw ? req.best_parent_hw->core : NULL;

		parent = req.best_parent_hw ? req.best_parent_hw->core : NULL;
@@ -2325,8 +2352,12 @@ static unsigned long clk_core_req_round_rate_nolock(struct clk_core *core, 




	clk_core_init_rate_req(core, &req, req_rate);

	clk_core_init_rate_req(core, &req, req_rate);





	trace_clk_rate_request_start(&req);



	ret = clk_core_round_rate_nolock(core, &req);

	ret = clk_core_round_rate_nolock(core, &req);





	trace_clk_rate_request_done(&req);



	/* restore the protection */

	/* restore the protection */

	clk_core_rate_restore_protect(core, cnt);

	clk_core_rate_restore_protect(core, cnt);

include/trace/events/clk.h

+43 −0
Original line number Original line Diff line number Diff line
@@ -264,6 +264,49 @@ DEFINE_EVENT(clk_duty_cycle, clk_set_duty_cycle_complete, 
	TP_ARGS(core, duty)

	TP_ARGS(core, duty)

);

);





DECLARE_EVENT_CLASS(clk_rate_request,



	TP_PROTO(struct clk_rate_request *req),



	TP_ARGS(req),



	TP_STRUCT__entry(

		__string(        name, req->core ? req->core->name : "none")

		__string(       pname, req->best_parent_hw ? clk_hw_get_name(req->best_parent_hw) : "none" )

		__field(unsigned long,           min                       )

		__field(unsigned long,           max                       )

		__field(unsigned long,           prate                     )

	),



	TP_fast_assign(

		__assign_str(name, req->core ? req->core->name : "none");

		__assign_str(pname, req->best_parent_hw ? clk_hw_get_name(req->best_parent_hw) : "none");

		__entry->min = req->min_rate;

		__entry->max = req->max_rate;

		__entry->prate = req->best_parent_rate;

	),



	TP_printk("%s min %lu max %lu, parent %s (%lu)", __get_str(name),

		  (unsigned long)__entry->min,

		  (unsigned long)__entry->max,

		  __get_str(pname),

		  (unsigned long)__entry->prate)

);



DEFINE_EVENT(clk_rate_request, clk_rate_request_start,



	TP_PROTO(struct clk_rate_request *req),



	TP_ARGS(req)

);



DEFINE_EVENT(clk_rate_request, clk_rate_request_done,



	TP_PROTO(struct clk_rate_request *req),



	TP_ARGS(req)

);



#endif /* _TRACE_CLK_H */

#endif /* _TRACE_CLK_H */





/* This part must be outside protection */

/* This part must be outside protection */