On Tue, Jan 14, 2025 at 10:23:42AM +0100, Daniel Lezcano wrote: > > Hi Nicolas, > > On 13/01/2025 14:27, Nícolas F. R. A. Prado wrote: > > When configured in filtered mode, the LVTS thermal controller will > > monitor the temperature from the sensors and trigger an interrupt once a > > thermal threshold is crossed. > > > > Currently this is true even during suspend and resume. The problem with > > that is that when enabling the internal clock of the LVTS controller in > > lvts_ctrl_set_enable() during resume, the temperature reading can glitch > > and appear much higher than the real one, resulting in a spurious > > interrupt getting generated. > > > > Disable the temperature monitoring and give some time for the signals to > > stabilize during suspend in order to prevent such spurious interrupts. > > > > Cc: stable@xxxxxxxxxxxxxxx > > Reported-by: Hsin-Te Yuan <yuanhsinte@xxxxxxxxxxxx> > > Closes: https://lore.kernel.org/all/20241108-lvts-v1-1-eee339c6ca20@xxxxxxxxxxxx/ > > Fixes: 8137bb90600d ("thermal/drivers/mediatek/lvts_thermal: Add suspend and resume") > > Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx> > > Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx> > > --- > > drivers/thermal/mediatek/lvts_thermal.c | 36 +++++++++++++++++++++++++++++++-- > > 1 file changed, 34 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c > > index 07f7f3b7a2fb569cfc300dc2126ea426e161adff..a1a438ebad33c1fff8ca9781e12ef9e278eef785 100644 > > --- a/drivers/thermal/mediatek/lvts_thermal.c > > +++ b/drivers/thermal/mediatek/lvts_thermal.c > > @@ -860,6 +860,32 @@ static int lvts_ctrl_init(struct device *dev, struct lvts_domain *lvts_td, > > return 0; > > } > > +static void lvts_ctrl_monitor_enable(struct device *dev, struct lvts_ctrl *lvts_ctrl, bool enable) > > +{ > > + /* > > + * Bitmaps to enable each sensor on filtered mode in the MONCTL0 > > + * register. > > + */ > > + static const u8 sensor_filt_bitmap[] = { BIT(0), BIT(1), BIT(2), BIT(3) }; > > + u32 sensor_map = 0; > > + int i; > > + > > + if (lvts_ctrl->mode != LVTS_MSR_FILTERED_MODE) > > + return; > > + > > + if (enable) { > > + lvts_for_each_valid_sensor(i, lvts_ctrl) > > + sensor_map |= sensor_filt_bitmap[i]; > > + } > > + > > + /* > > + * Bits: > > + * 9: Single point access flow > > + * 0-3: Enable sensing point 0-3 > > + */ > > + writel(sensor_map | BIT(9), LVTS_MONCTL0(lvts_ctrl->base)); > > +} > > + > > /* > > * At this point the configuration register is the only place in the > > * driver where we write multiple values. Per hardware constraint, > > @@ -1381,8 +1407,11 @@ static int lvts_suspend(struct device *dev) > > lvts_td = dev_get_drvdata(dev); > > - for (i = 0; i < lvts_td->num_lvts_ctrl; i++) > > + for (i = 0; i < lvts_td->num_lvts_ctrl; i++) { > > + lvts_ctrl_monitor_enable(dev, &lvts_td->lvts_ctrl[i], false); > > + usleep_range(100, 200); > > From where this delay is coming from ? That's empirical. I tested several times doing system suspend and resume on the machines hooked to our lab and that was the minimum delay I could find that still never resulted in the spurious readings. Unfortunately the technical documentation I have access to never even mentioned that this issue could arise, let alone what the timing constraints were, so this had to be figured out empirically. Thanks, Nícolas
