[PATCH 2/5] arm64: dts: imx8mq-phanbell: Do not hardcode a cooling state that may not exist

[Rudi Heitbaum]

The cpu_alert1 map asks for cooling states 0 to 2, to exclude the two
highest operating points. How many operating points exist depends on the
speed grade: a53_opp_table gates each entry on opp-supported-hw, and a
grade 3 / segment 0 part gets only two of the four, 1.0GHz and 1.5GHz.
cpufreq-cpu0 then has max_state 1 and the bind is rejected:

  thermal thermal_zone0: binding cdev cpufreq-cpu0 to trip 3 failed: -22

thermal_bind_cdev_to_trip() returns -EINVAL when upper exceeds
max_state. The trip is left with no cooling device at all.

Use THERMAL_NO_LIMIT so the map means "all available states" and adapts
to whatever the part provides. On a device with the full table this is
still the hotter of the two trips and still allows more throttling than
cpu_alert0; on a two operating point part the two trips coincide, which
is the best that can be done there.

cpu_alert0 is unaffected: its upper bound of 1 is valid either way, which
is why frequency throttling works at 75C despite this failure.

Signed-off-by: Rudi Heitbaum <rudi at heitbaum.com>
---
 arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts b/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
index c06a787a4013..4ad206f5a9d1 100644
--- a/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
+++ b/arch/arm64/boot/dts/freescale/imx8mq-phanbell.dts
@@ -101,7 +101,7 @@ map0 {
 		map1 {
 			trip = <&cpu_alert1>;
 			cooling-device =
-			<&A53_0 0 2>; /* Exclude two highest OPPs */
+			<&A53_0 0 THERMAL_NO_LIMIT>;
 		};
 
 		map4 {
-- 
2.53.0