+ Viresh for help. > -----Original Message----- > From: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> > Sent: 2019年5月10日 15:17 > To: Andy Tang <andy.tang@xxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx> > Cc: Leo Li <leoyang.li@xxxxxxx>; robh+dt@xxxxxxxxxx; > mark.rutland@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-pm@xxxxxxxxxxxxxxx; rui.zhang@xxxxxxxxx; edubezval@xxxxxxxxx > Subject: Re: [EXT] Re: [PATCH v6] arm64: dts: ls1088a: add one more thermal > zone node > > Caution: EXT Email > > On 10/05/2019 05:40, Andy Tang wrote: > >> -----Original Message----- > >> From: Shawn Guo <shawnguo@xxxxxxxxxx> > >> Sent: 2019年5月10日 11:14 > >> To: Andy Tang <andy.tang@xxxxxxx> > >> Cc: Leo Li <leoyang.li@xxxxxxx>; robh+dt@xxxxxxxxxx; > >> mark.rutland@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > >> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > >> linux-pm@xxxxxxxxxxxxxxx; daniel.lezcano@xxxxxxxxxx; > >> rui.zhang@xxxxxxxxx; edubezval@xxxxxxxxx > >> Subject: [EXT] Re: [PATCH v6] arm64: dts: ls1088a: add one more > >> thermal zone node > >> > >> Caution: EXT Email > >> > >> On Tue, Apr 23, 2019 at 10:25:07AM +0800, Yuantian Tang wrote: > >>> Ls1088a has 2 thermal sensors, core cluster and SoC platform. Core > >>> cluster sensor is used to monitor the temperature of core and SoC > >>> platform is for platform. The current dts only support the first sensor. > >>> This patch adds the second sensor node to dts to enable it. > >>> > >>> Signed-off-by: Yuantian Tang <andy.tang@xxxxxxx> > >>> --- > >>> v6: > >>> - add cooling device map to cpu0-7 in platform node. > > I like to explain a little. I think it makes sense that multiple thermal zone > map to same cooling device. > > In this way, no matter which thermal zone raises a temp alarm, it can call > cooling device to chill out. > > I also asked cpufreq maintainer about the cooling map issue, he think it > would be fine. > > I have tested and no issue found. > > > > Daniel, what's your thought? > > If there are multiple thermal zones, they will be managed by different > instances of a thermal governor. Each instances will act on the shared cooling > device and will collide in their decisions: > > - If the sensors are closed, their behavior will be similar regarding the > temperature. The governors may take the same decision for the cooling > device. But in such case having just one thermal zone managed is enough. > > - If the sensors are not closed, their behavior will be different regarding the > temperature. The governors will take different decision regarding the cooling > device (one will decrease the freq, other will increase the freq). > > As the thermal governors are not able to manage several thermal zones and > there is one cooling device (the cpu cooling device), this setup won't work as > expected IMO. > > The setup making sense is having a thermal zone per 'cluster' and a cooling > device per 'cluster'. That means the platform has one clock line per 'cluster'. > The thermal management happens in a self-contained thermal zone (one > cooling device - one governor - one thermal zone). > > In the case of HMP, other combinations are possible to be optimal. Hi Viresh, I want to map multiple thermal zones to the same cooling device. The above is the discussion about it. It seems reasonable. But I am not expert on this. Could you please provide some thoughts? Thanks. BR, Andy > > > > -- > > <https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww. > linaro.org%2F&data=02%7C01%7Candy.tang%40nxp.com%7C935b7a08 > 31cc466da40808d6d5176f8e%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0 > %7C0%7C636930693965540189&sdata=WK9NDBVwzhCC9WMkmjLObJ > OBQwRG%2Fboed%2FKx18xiBNQ%3D&reserved=0> Linaro.org │ Open > source software for ARM SoCs > > Follow Linaro: > <https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww. > facebook.com%2Fpages%2FLinaro&data=02%7C01%7Candy.tang%40nx > p.com%7C935b7a0831cc466da40808d6d5176f8e%7C686ea1d3bc2b4c6fa92c > d99c5c301635%7C0%7C0%7C636930693965550202&sdata=O0mWO76 > 9sK2ZMGX9AxgLGYNVfkFHBD4ZIGCclttvyPI%3D&reserved=0> > Facebook | > <https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Ftwitte > r.com%2F%23!%2Flinaroorg&data=02%7C01%7Candy.tang%40nxp.com > %7C935b7a0831cc466da40808d6d5176f8e%7C686ea1d3bc2b4c6fa92cd99c5 > c301635%7C0%7C0%7C636930693965550202&sdata=tV%2Bi8Bk3OqO > h%2FZHpBr2NQDACVvtGi8KNGQt5dZaTeyg%3D&reserved=0> Twitter | > <https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww. > linaro.org%2Flinaro-blog%2F&data=02%7C01%7Candy.tang%40nxp.co > m%7C935b7a0831cc466da40808d6d5176f8e%7C686ea1d3bc2b4c6fa92cd99 > c5c301635%7C0%7C0%7C636930693965550202&sdata=0E8a938xEt7l2 > MBLnMETsCQKfhJMgmzFNtuCKPXf5SY%3D&reserved=0> Blog
