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@vger.kernel.org Reported-by: Hsin-Te Yuan yuanhsinte@chromium.org Closes: https://lore.kernel.org/all/20241108-lvts-v1-1-eee339c6ca20@chromium.org/ Fixes: 8137bb90600d ("thermal/drivers/mediatek/lvts_thermal: Add suspend and resume") Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Signed-off-by: Nícolas F. R. A. Prado nfraprado@collabora.com
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