On Wed, Jul 17, 2024 at 09:45:02PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > The iwlwifi wireless driver registers a thermal zone that is only needed > when the network interface handled by it is up and it wants that thermal > zone to be effectively ignored by the core otherwise. > > Before commit a8a261774466 ("thermal: core: Call monitor_thermal_zone() > if zone temperature is invalid") that could be achieved by returning > an error code from the thermal zone's .get_temp() callback because the > core did not really handle errors returned by it almost at all. > However, commit a8a261774466 made the core attempt to recover from the > situation in which the temperature of a thermal zone cannot be > determined due to errors returned by its .get_temp() and is always > invalid from the core's perspective. > > That was done because there are thermal zones in which .get_temp() > returns errors to start with due to some difficulties related to the > initialization ordering, but then it will start to produce valid > temperature values at one point. > > Unfortunately, the simple approach taken by commit a8a261774466, > which is to poll the thermal zone periodically until its .get_temp() > callback starts to return valid temperature values, is at odds with > the special thermal zone in iwlwifi in which .get_temp() may always > return an error because its network interface may always be down. If > that happens, every attempt to invoke the thermal zone's .get_temp() > callback resulting in an error causes the thermal core to print a > dev_warn() message to the kernel log which is super-noisy. > > To address this problem, make the core handle the case in which > .get_temp() returns 0, but the temperature value returned by it > is not actually valid, in a special way. Namely, make the core > completely ignore the invalid temperature value coming from > .get_temp() in that case, which requires folding in > update_temperature() into its caller and a few related changes. > > On the iwlwifi side, modify iwl_mvm_tzone_get_temp() to return 0 > and put THERMAL_TEMP_INVALID into the temperature return memory > location instead of returning an error when the firmware is not > running or it is not of the right type. > > Also, to clearly separate the handling of invalid temperature > values from the thermal zone initialization, introduce a special > THERMAL_TEMP_INIT value specifically for the latter purpose. > > Fixes: a8a261774466 ("thermal: core: Call monitor_thermal_zone() if zone temperature is invalid") > Closes: https://lore.kernel.org/linux-pm/20240715044527.GA1544@sol.localdomain/ > Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx> > Reported-by: Stefan Lippers-Hollmann <s.l-h@xxxxxx> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=201761 > Tested-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> > Tested-by: Stefan Lippers-Hollmann <s.l-h@xxxxxx> > Cc: 6.10+ <stable@xxxxxxxxxxxxxxx> # 6.10+ > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > --- > > v1 -> v2: > * It is safer to retain the old behavior in thermal_zone_get_temp(), > which is the second place where the .get_temp() zone callback is > used, so make it return -ENODATA if the temperature value coming > from that callback is invalid. > * Add Tested-by: for Stefan. > > I have retained the previous Tested-by because the part of the patch that has > been tested remains unchanged. > > --- > drivers/net/wireless/intel/iwlwifi/mvm/tt.c | 7 +++ > drivers/thermal/thermal_core.c | 51 +++++++++++++--------------- > drivers/thermal/thermal_core.h | 3 + > drivers/thermal/thermal_helpers.c | 2 + > 4 files changed, 35 insertions(+), 28 deletions(-) This makes the log messages go away for me. However I had to resolve a conflict in drivers/net/wireless/intel/iwlwifi/mvm/tt.c to apply this patch to the latest upstream. - Eric