[RFC PATCH v2 10/10] arm_mpam: resctrl: Update the comment on monitoring domain setup

[Reinette Chatre]

The comment in mpam_resctrl_setup_mon_domain() explains that the L3
component IDs need to be used for a monitoring domain because there may
be no control component for the L3. It also describes searching each
event's class for a component with overlapping CPUs.

Neither matches the code. The monitoring domain has its own structure
and is set up independently of the control domain, so whether a control
component exists has no bearing on it. Each event's class must have a
component that contains the CPU, and all components of the domain must
cover the same CPUs, which is stricter than overlapping.

Rewrite the comment to say where the domain's ID comes from and what is
required of the components that back the domain's events.

No functional change.

Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
Note to maintainers: This comment update is kept as a separate patch to
make it easy to review. It can be folded into "arm_mpam: resctrl: Give
the monitoring domain its own structure" and "arm_mpam: resctrl: Require
monitoring components to cover the same CPUs" if preferred.
---
 drivers/resctrl/mpam_resctrl.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index c3ea61a40bb2..61fbde9c0960 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1647,11 +1647,12 @@ static int mpam_resctrl_setup_mon_domain(unsigned int cpu,
 	int err;
 
 	/*
-	 * Even if the monitor domain is backed by a different
-	 * component, the L3 component IDs need to be used... only
-	 * there may be no ctrl_comp for the L3.
-	 * Search each event's class list for a component with
-	 * overlapping CPUs and set up the dom->mon_comp array.
+	 * The monitoring domain takes the L3 cache ID as its ID even when its
+	 * events are backed by components of other classes, see
+	 * mpam_resctrl_pick_domain_id().
+	 * Find the component of each event's class that contains the CPU and
+	 * set up the dom->mon_comp array. All these components must cover the
+	 * same CPUs.
 	 */
 
 	for_each_mpam_resctrl_mon(mon, eventid) {
-- 
2.55.0