Re: [PATCH] drm/xe/hwmon: refresh Battlemage thermal telemetry under force-wake

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] drm/xe: fan telemetry lacks Battlemage thermal force-wake workaround
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commit a9faaf30cbf789280ad52add1cf188270e8ccad9
Author: Constantinos Chalkias <cch@e-psn.eu>

drm/xe/hwmon: refresh Battlemage thermal telemetry under force-wake

This commit works around stale thermal telemetry on Battlemage by
acquiring the GT force-wake domain and waiting 500-1000 us before
reading temperature registers.

> drm/xe/hwmon: refresh Battlemage thermal telemetry under force-wake
> 
> On Battlemage, thermal telemetry can remain stale after the GT returns
> to RC6 following sustained workloads.
> 
> On an Intel Arc Pro B70, package and VRAM temperature telemetry may stop
> refreshing after a long inference workload. Fan telemetry can also
> become invalid while the physical blower remains elevated.

[Severity: Medium]
The commit message states that fan telemetry can become invalid, but the
patch only applies the force-wake and delay workaround to temperature and
VRAM channels via xe_hwmon_temp_mmio_read().

Does xe_hwmon_fan_input_read() also need this workaround? Currently, it
continues to read REG_FAN_SPEED directly via xe_mmio_read32() without
acquiring force-wake or delaying:

drivers/gpu/drm/xe/xe_hwmon.c:xe_hwmon_fan_input_read() {
    ...
	mutex_lock(&hwmon->hwmon_lock);

	reg_val = xe_mmio_read32(mmio, xe_hwmon_get_reg(hwmon, REG_FAN_SPEED, channel));
	time_now = get_jiffies_64();
    ...
}

Will fan telemetry still remain susceptible to staleness on Battlemage
without the workaround?

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Sashiko AI review · https://sashiko.dev/#/patchset/20261012104245.2108030-1-cch@e-psn.eu?part=1