[Intel-gfx] [PATCH 2/3] drm/i915/guc: Disable PL1 power limit when loading GuC firmware

Ashutosh Dixit
2023-04-20T16:41:06Z

On dGfx, the PL1 power limit being enabled and set to a low value results
in a low GPU operating freq. It also negates the freq raise operation which
is done before GuC firmware load. As a result GuC firmware load can time
out. Such timeouts were seen in the GL #8062 bug below (where the PL1 power
limit was enabled and set to a low value). Therefore disable the PL1 power
limit when allowed by HW when loading GuC firmware.

v2:
- Take mutex (to disallow writes to power1_max) across GuC reset/fw load
- Add hwm_power_max_restore to error return code path

v3 (Jani N):
- Add/remove explanatory comments
- Function renames
- Type corrections
- Locking annotation

v4:
- Don't hold the lock across GuC reset (Rodrigo)
- New locking scheme (suggested by Rodrigo)
- Eliminate rpm_get in power_max_disable/restore, not needed (Tvrtko)

v5:
- Fix uninitialized pl1en variable compile warning reported by kernel
build robot by creating new err_rps label

Link: https://gitlab.freedesktop.org/drm/intel/-/issues/8062
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
drivers/gpu/drm/i915/gt/uc/intel_uc.c | 13 +++++++--
drivers/gpu/drm/i915/i915_hwmon.c | 40 +++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_hwmon.h | 7 +++++
3 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index 4ccb4be4c9cba..996168312340e 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -18,6 +18,7 @@
#include "intel_uc.h"

#include "i915_drv.h"
+#include "i915_hwmon.h"

static const struct intel_uc_ops uc_ops_off;
static const struct intel_uc_ops uc_ops_on;
@@ -461,6 +462,7 @@ static int __uc_init_hw(struct intel_uc *uc)
struct intel_guc *guc = &uc->guc;
struct intel_huc *huc = &uc->huc;
int ret, attempts;
+ bool pl1en;

GEM_BUG_ON(!intel_uc_supports_guc(uc));
GEM_BUG_ON(!intel_uc_wants_guc(uc));
@@ -491,6 +493,9 @@ static int __uc_init_hw(struct intel_uc *uc)
else
attempts = 1;

+ /* Disable a potentially low PL1 power limit to allow freq to be raised */
+ i915_hwmon_power_max_disable(gt->i915, &pl1en);
+
intel_rps_raise_unslice(&uc_to_gt(uc)->rps);

while (attempts--) {
@@ -500,7 +505,7 @@ static int __uc_init_hw(struct intel_uc *uc)
*/
ret = __uc_sanitize(uc);
if (ret)
- goto err_out;
+ goto err_rps;

intel_huc_fw_upload(huc);
intel_guc_ads_reset(guc);
@@ -547,6 +552,8 @@ static int __uc_init_hw(struct intel_uc *uc)
intel_rps_lower_unslice(&uc_to_gt(uc)->rps);
}

+ i915_hwmon_power_max_restore(gt->i915, pl1en);
+
guc_info(guc, "submission %s\n", str_enabled_disabled(intel_uc_uses_guc_submission(uc)));
guc_info(guc, "SLPC %s\n", str_enabled_disabled(intel_uc_uses_guc_slpc(uc)));

@@ -559,10 +566,12 @@ static int __uc_init_hw(struct intel_uc *uc)
intel_guc_submission_disable(guc);
err_log_capture:
__uc_capture_load_err_log(uc);
-err_out:
+err_rps:
/* Return GT back to RPn */
intel_rps_lower_unslice(&uc_to_gt(uc)->rps);

+ i915_hwmon_power_max_restore(gt->i915, pl1en);
+err_out:
__uc_sanitize(uc);

if (!ret) {
diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
index 7f44e809ca155..9ab8971679fe3 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.c
+++ b/drivers/gpu/drm/i915/i915_hwmon.c
@@ -50,6 +50,7 @@ struct hwm_drvdata {
struct hwm_energy_info ei; /* Energy info for energy1_input */
char name[12];
int gt_n;
+ bool reset_in_progress;
};

struct i915_hwmon {
@@ -400,6 +401,10 @@ hwm_power_max_write(struct hwm_drvdata *ddat, long val)
u32 nval;

mutex_lock(&hwmon->hwmon_lock);
+ if (hwmon->ddat.reset_in_progress) {
+ ret = -EAGAIN;
+ goto unlock;
+ }
wakeref = intel_runtime_pm_get(ddat->uncore->rpm);

/* Disable PL1 limit and verify, because the limit cannot be disabled on all platforms */
@@ -421,6 +426,7 @@ hwm_power_max_write(struct hwm_drvdata *ddat, long val)
PKG_PWR_LIM_1_EN | PKG_PWR_LIM_1, nval);
exit:
intel_runtime_pm_put(ddat->uncore->rpm, wakeref);
+unlock:
mutex_unlock(&hwmon->hwmon_lock);
return ret;
}
@@ -472,6 +478,40 @@ hwm_power_write(struct hwm_drvdata *ddat, u32 attr, int chan, long val)
}
}

+void i915_hwmon_power_max_disable(struct drm_i915_private *i915, bool *old)
+{
+ struct i915_hwmon *hwmon = i915->hwmon;
+ u32 r;
+
+ if (!hwmon || !i915_mmio_reg_valid(hwmon->rg.pkg_rapl_limit))
+ return;
+
+ mutex_lock(&hwmon->hwmon_lock);
+
+ hwmon->ddat.reset_in_progress = true;
+ r = intel_uncore_rmw(hwmon->ddat.uncore, hwmon->rg.pkg_rapl_limit,
+ PKG_PWR_LIM_1_EN, 0);
+ *old = !!(r & PKG_PWR_LIM_1_EN);
+
+ mutex_unlock(&hwmon->hwmon_lock);
+}
+
+void i915_hwmon_power_max_restore(struct drm_i915_private *i915, bool old)
+{
+ struct i915_hwmon *hwmon = i915->hwmon;
+
+ if (!hwmon || !i915_mmio_reg_valid(hwmon->rg.pkg_rapl_limit))
+ return;
+
+ mutex_lock(&hwmon->hwmon_lock);
+
+ 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;
+
+ mutex_unlock(&hwmon->hwmon_lock);
+}
+
static umode_t
hwm_energy_is_visible(const struct hwm_drvdata *ddat, u32 attr)
{
diff --git a/drivers/gpu/drm/i915/i915_hwmon.h b/drivers/gpu/drm/i915/i915_hwmon.h
index 7ca9cf2c34c96..0fcb7de844061 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.h
+++ b/drivers/gpu/drm/i915/i915_hwmon.h
@@ -7,14 +7,21 @@
#ifndef __I915_HWMON_H__
#define __I915_HWMON_H__

+#include <linux/types.h>
+
struct drm_i915_private;
+struct intel_gt;

#if IS_REACHABLE(CONFIG_HWMON)
void i915_hwmon_register(struct drm_i915_private *i915);
void i915_hwmon_unregister(struct drm_i915_private *i915);
+void i915_hwmon_power_max_disable(struct drm_i915_private *i915, bool *old);
+void i915_hwmon_power_max_restore(struct drm_i915_private *i915, bool old);
#else
static inline void i915_hwmon_register(struct drm_i915_private *i915) { };
static inline void i915_hwmon_unregister(struct drm_i915_private *i915) { };
+static inline void i915_hwmon_power_max_disable(struct drm_i915_private *i915, bool *old) { };
+static inline void i915_hwmon_power_max_restore(struct drm_i915_private *i915, bool old) { };
#endif

#endif /* __I915_HWMON_H__ */
--
2.38.0