On Thursday, June 6, 2024 6:39:02 PM CEST Daniel Lezcano wrote:
> On 06/06/2024 18:08, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxx
> > Reported-by: Laura Nao <laura.nao@xxxxxxxxxxxxx>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > ---
> >
> > v1 -> v2:
> > * Instead of making the thermal debug code effectively ignore the invalid
> > initial cooling device state, simply don't register thermal debugfs for
> > a cooling device if its initial state returned by the driver's
> > .get_cur_state() is invalid (Daniel).
> >
> > Laura, please test this one even though I don't see why it wouldn't work for
> > you if the v1 did.
> >
> > ---
> > drivers/thermal/thermal_core.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > Index: linux-pm/drivers/thermal/thermal_core.c
> > ===================================================================
> > --- linux-pm.orig/drivers/thermal/thermal_core.c
> > +++ linux-pm/drivers/thermal/thermal_core.c
> > @@ -1001,7 +1001,7 @@ __thermal_cooling_device_register(struct
> >
> > ret = cdev->ops->get_cur_state(cdev, ¤t_state);
> > if (ret)
> > - goto out_cdev_type;
> > + current_state = ULONG_MAX;
>
> Why not move the section ? So we end up below.
Because it's fewer changes in this patch and it doesn't matter.
> >
> > thermal_cooling_device_setup_sysfs(cdev);
> >
> > @@ -1016,7 +1016,8 @@ __thermal_cooling_device_register(struct
> > return ERR_PTR(ret);
> > }
> >
> > - thermal_debug_cdev_add(cdev, current_state);
> > + if (current_state <= cdev->max_state)
> > + thermal_debug_cdev_add(cdev, current_state);
>
> ret = cdev->ops->get_cur_state(cdev, ¤t_state);
> if (!ret)
> thermal_debug_cdev_add(cdev, current_state);
So the current_state <= cdev->max_state is actually useful regardless and
consistent with the analogous check in thermal_cooling_device_update().
> Additionally a comment here to explain why get_cur_state can fail and
> telling it is up to the driver to fix its routine?
I've added a comment in v3.
>
> > /* Add 'this' new cdev to the global cdev list */
> > mutex_lock(&thermal_list_lock);
> >
> >
> >
>
>
