From: Rafael J. Wysocki Date: Thu, 6 Jun 2024 18:27:19 +0000 (+0200) Subject: thermal: core: Do not fail cdev registration because of invalid initial state X-Git-Tag: v6.10-rc4~25^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1af89dedc8a5;p=thirdparty%2Flinux.git thermal: core: Do not fail cdev registration because of invalid initial state It is reported that commit 31a0fa0019b0 ("thermal/debugfs: Pass cooling device state to thermal_debug_cdev_add()") causes the ACPI fan driver to fail probing on some systems which turns out to be due to the _FST control method returning an invalid value until _FSL is first evaluated for the given fan. If this happens, the .get_cur_state() cooling device callback returns an error and __thermal_cooling_device_register() fails as uses that callback after commit 31a0fa0019b0. Arguably, _FST should not return an invalid value even if it is evaluated before _FSL, so this may be regarded as a platform firmware issue, but at the same time it is not a good enough reason for failing the cooling device registration where the initial cooling device state is only needed to initialize a thermal debug facility. Accordingly, modify __thermal_cooling_device_register() to avoid calling thermal_debug_cdev_add() instead of returning an error if the initial .get_cur_state() callback invocation fails. Fixes: 31a0fa0019b0 ("thermal/debugfs: Pass cooling device state to thermal_debug_cdev_add()") Closes: https://lore.kernel.org/linux-acpi/20240530153727.843378-1-laura.nao@collabora.com Reported-by: Laura Nao Signed-off-by: Rafael J. Wysocki Acked-by: Daniel Lezcano Tested-by: Laura Nao --- diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c index 30567b4994551..d70e76dd3c943 100644 --- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -999,9 +999,17 @@ __thermal_cooling_device_register(struct device_node *np, if (ret) goto out_cdev_type; + /* + * The cooling device's current state is only needed for debug + * initialization below, so a failure to get it does not cause + * the entire cooling device initialization to fail. However, + * the debug will not work for the device if its initial state + * cannot be determined and drivers are responsible for ensuring + * that this will not happen. + */ ret = cdev->ops->get_cur_state(cdev, ¤t_state); if (ret) - goto out_cdev_type; + current_state = ULONG_MAX; thermal_cooling_device_setup_sysfs(cdev); @@ -1016,7 +1024,8 @@ __thermal_cooling_device_register(struct device_node *np, return ERR_PTR(ret); } - thermal_debug_cdev_add(cdev, current_state); + if (current_state <= cdev->max_state) + thermal_debug_cdev_add(cdev, current_state); /* Add 'this' new cdev to the global cdev list */ mutex_lock(&thermal_list_lock);