OA reports in the OA buffer contain an OA timestamp field that helps user calculate delta between 2 OA reports. The calculation relies on the CS timestamp frequency to convert the timestamp value to nanoseconds. The CS timestamp frequency is a function of the CTC_SHIFT value in RPM_CONFIG0. In DG2, OA unit assumes that the CTC_SHIFT is 3, instead of using the actual value from RPM_CONFIG0. At the user level, this results in an error in calculating delta between 2 OA reports since the OA timestamp is not shifted in the same manner as CS timestamp. To resolve this, return actual OA timestamp frequency to the user in i915_getparam_ioctl. Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_getparam.c | 3 +++ drivers/gpu/drm/i915/i915_perf.c | 30 ++++++++++++++++++++++++++-- drivers/gpu/drm/i915/i915_perf.h | 2 ++ include/uapi/drm/i915_drm.h | 6 ++++++ 4 files changed, 39 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_getparam.c b/drivers/gpu/drm/i915/i915_getparam.c index 6fd15b39570c..cdb2208ecabd 100644 --- a/drivers/gpu/drm/i915/i915_getparam.c +++ b/drivers/gpu/drm/i915/i915_getparam.c @@ -175,6 +175,9 @@ int i915_getparam_ioctl(struct drm_device *dev, void *data, case I915_PARAM_PERF_REVISION: value = i915_perf_ioctl_version(); break; + case I915_PARAM_OA_TIMESTAMP_FREQUENCY: + value = i915_perf_oa_timestamp_frequency(i915); + break; default: DRM_DEBUG("Unknown parameter %d\n", param->param); return -EINVAL; diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c index ce379ac88a60..00371b4146d7 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -3189,6 +3189,30 @@ get_sseu_config(struct intel_sseu *out_sseu, return i915_gem_user_to_context_sseu(engine->gt, drm_sseu, out_sseu); } +/* + * OA timestamp frequency = CS timestamp frequency in most platforms. On some + * platforms OA unit ignores the CTC_SHIFT and the 2 timestamps differ. In such + * cases, return the adjusted CS timestamp frequency to the user. + */ +u32 i915_perf_oa_timestamp_frequency(struct drm_i915_private *i915) +{ + /* Wa_18013179988:dg2 */ + if (IS_DG2(i915)) { + intel_wakeref_t wakeref; + u32 reg, shift; + + with_intel_runtime_pm(to_gt(i915)->uncore->rpm, wakeref) + reg = intel_uncore_read(to_gt(i915)->uncore, RPM_CONFIG0); + + shift = (reg & GEN10_RPM_CONFIG0_CTC_SHIFT_PARAMETER_MASK) >> + GEN10_RPM_CONFIG0_CTC_SHIFT_PARAMETER_SHIFT; + + return to_gt(i915)->clock_frequency << (3 - shift); + } + + return to_gt(i915)->clock_frequency; +} + /** * i915_oa_stream_init - validate combined props for OA stream and init * @stream: An i915 perf stream @@ -3913,8 +3937,10 @@ i915_perf_open_ioctl_locked(struct i915_perf *perf, static u64 oa_exponent_to_ns(struct i915_perf *perf, int exponent) { - return intel_gt_clock_interval_to_ns(to_gt(perf->i915), - 2ULL << exponent); + u64 nom = (2ULL << exponent) * NSEC_PER_SEC; + u32 den = i915_perf_oa_timestamp_frequency(perf->i915); + + return div_u64(nom + den - 1, den); } static __always_inline bool diff --git a/drivers/gpu/drm/i915/i915_perf.h b/drivers/gpu/drm/i915/i915_perf.h index 1d1329e5af3a..f96e09a4af04 100644 --- a/drivers/gpu/drm/i915/i915_perf.h +++ b/drivers/gpu/drm/i915/i915_perf.h @@ -57,4 +57,6 @@ static inline void i915_oa_config_put(struct i915_oa_config *oa_config) kref_put(&oa_config->ref, i915_oa_config_release); } +u32 i915_perf_oa_timestamp_frequency(struct drm_i915_private *i915); + #endif /* __I915_PERF_H__ */ diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index 9168412e0da8..18ada8ce1a58 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -749,6 +749,12 @@ typedef struct drm_i915_irq_wait { /* Query if the kernel supports the I915_USERPTR_PROBE flag. */ #define I915_PARAM_HAS_USERPTR_PROBE 56 +/* + * Frequency of the timestamps in OA reports. This used to be the same as the CS + * timestamp frequency, but differs on some platforms. + */ +#define I915_PARAM_OA_TIMESTAMP_FREQUENCY 57 + /* Must be kept compact -- no holes and well documented */ /** -- 2.25.1