[Intel-gfx] [PATCH 3/3] drm/i915/hwmon: Block waiting for GuC reset to complete

Ashutosh Dixit
2023-04-20T16:41:05Z

Instead of erroring out when GuC reset is in progress, block waiting for
GuC reset to complete which is a more reasonable uapi behavior.

v2: Avoid race between wake_up_all and waiting for wakeup (Rodrigo)
v3: Remove timeout when blocked (Tvrtko)

Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
drivers/gpu/drm/i915/i915_hwmon.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
index 9ab8971679fe3..a3bdd9f68a458 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.c
+++ b/drivers/gpu/drm/i915/i915_hwmon.c
@@ -51,6 +51,7 @@ struct hwm_drvdata {
char name[12];
int gt_n;
bool reset_in_progress;
+ wait_queue_head_t waitq;
};

struct i915_hwmon {
@@ -397,14 +398,32 @@ hwm_power_max_write(struct hwm_drvdata *ddat, long val)
{
struct i915_hwmon *hwmon = ddat->hwmon;
intel_wakeref_t wakeref;
+ DEFINE_WAIT(wait);
int ret = 0;
u32 nval;

- mutex_lock(&hwmon->hwmon_lock);
- if (hwmon->ddat.reset_in_progress) {
- ret = -EAGAIN;
- goto unlock;
+ /* Block waiting for GuC reset to complete when needed */
+ for (;;) {
+ mutex_lock(&hwmon->hwmon_lock);
+
+ prepare_to_wait(&ddat->waitq, &wait, TASK_INTERRUPTIBLE);
+
+ if (!hwmon->ddat.reset_in_progress)
+ break;
+
+ if (signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
+
+ mutex_unlock(&hwmon->hwmon_lock);
+
+ schedule();
}
+ finish_wait(&ddat->waitq, &wait);
+ if (ret)
+ goto unlock;
+
wakeref = intel_runtime_pm_get(ddat->uncore->rpm);

/* Disable PL1 limit and verify, because the limit cannot be disabled on all platforms */
@@ -508,6 +527,7 @@ void i915_hwmon_power_max_restore(struct drm_i915_private *i915, bool old)
intel_uncore_rmw(hwmon->ddat.uncore, hwmon->rg.pkg_rapl_limit,
PKG_PWR_LIM_1_EN, old ? PKG_PWR_LIM_1_EN : 0);
hwmon->ddat.reset_in_progress = false;
+ wake_up_all(&hwmon->ddat.waitq);

mutex_unlock(&hwmon->hwmon_lock);
}
@@ -784,6 +804,7 @@ void i915_hwmon_register(struct drm_i915_private *i915)
ddat->uncore = &i915->uncore;
snprintf(ddat->name, sizeof(ddat->name), "i915");
ddat->gt_n = -1;
+ init_waitqueue_head(&ddat->waitq);

for_each_gt(gt, i915, i) {
ddat_gt = hwmon->ddat_gt + i;
--
2.38.0