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SubjectRe: [PATCH v5 1/3] thermal: qcom-spmi: Use PMIC thermal stage 2 for critical trip points
Hi,

On Tue, Jul 24, 2018 at 4:46 PM, Matthias Kaehlcke <mka@chromium.org> wrote:
> +static int qpnp_tm_update_critical_trip_temp(struct qpnp_tm_chip *chip,
> + int temp)
> +{
> + u8 reg;
> + bool disable_s2_shutdown = false;
> + int ret;
> +
> + WARN_ON(!mutex_is_locked(&chip->lock));
> +
> + /*
> + * Default: S2 and S3 shutdown enabled, thresholds at
> + * 105C/125C/145C, monitoring at 25Hz
> + */
> + reg = SHUTDOWN_CTRL1_RATE_25HZ;
> +
> + if ((temp == THERMAL_TEMP_INVALID) ||
> + (temp < STAGE2_THRESHOLD_MIN)) {
> + chip->thresh = THRESH_MIN;
> + goto skip;
> + }
> +
> + if (temp <= STAGE2_THRESHOLD_MAX) {
> + chip->thresh = THRESH_MAX -
> + ((STAGE2_THRESHOLD_MAX - temp) /
> + TEMP_THRESH_STEP);
> + disable_s2_shutdown = true;
> + } else {
> + chip->thresh = THRESH_MAX;
> +
> + if (!IS_ERR(chip->adc))
> + disable_s2_shutdown = true;
> + else
> + dev_warn(chip->dev,
> + "No ADC is configured and critical temperature is above the maximum stage 2 threshold of 140°C! Configuring stage 2 shutdown at 140°C.\n");

Putting a non-ASCII character (the degree symbol) in your commit
message is one thing, but are you sure it's wise to put it in the
kernel logs?


> + }
> +
> +skip:
> + reg |= chip->thresh;
> + if (disable_s2_shutdown)
> + reg |= SHUTDOWN_CTRL1_OVERRIDE_S2;
> +
> + ret = qpnp_tm_write(chip, QPNP_TM_REG_SHUTDOWN_CTRL1, reg);
> + if (ret < 0)
> + return ret;
> +
> + return ret;

Simplify the above lines to:

return qpnp_tm_write(chip, QPNP_TM_REG_SHUTDOWN_CTRL1, reg);


> @@ -313,12 +441,7 @@ static int qpnp_tm_probe(struct platform_device *pdev)
> if (ret < 0)
> return ret;
>
> - chip->tz_dev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, chip,
> - &qpnp_tm_sensor_ops);
> - if (IS_ERR(chip->tz_dev)) {
> - dev_err(&pdev->dev, "failed to register sensor\n");
> - return PTR_ERR(chip->tz_dev);
> - }
> + chip->initialized = true;

Should we add "thermal_zone_device_update(chip->tz_dev,
THERMAL_EVENT_UNSPECIFIED);" here

...also: do we care about any type of locking for chip->initialized?
Technically we can be running on weakly ordered memory so if
qpnp_tm_update_temp_no_adc() is running on a different processor then
possibly it could still keep returning the default temperature for a
little while. We could try to analyze whether there's some sort of
implicit barrier or we could add manual memory barriers, but generally
I try to avoid that and just do the simple locking... What about just
setting chip-Initialized = true at the end of qpnp_tm_init() while the
mutex is still held?


I'd also love to hear from someone with more thermal framework
experience to make sure it's legit to return a default value if
someone calls us while we're initting. It seems sane to me but nice
to confirm it's OK.


Overall I like the idea of this patch so hopefully others do too.
Thanks for sending it out!


-Doug

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