Re: [Intel-gfx] [PATCH] drm/i915/rc6: GTC6_RESIDENCY_{LSB, MSB} Residency counter support

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 26/09/2022 09:45, Anshuman Gupta wrote:
> Adding support in drpc show debugfs to print the GT RPM Unit RC6
> residency. This GTC6_RESIDENCY_{LSB, MSB} will only increment when
> GT will be RC6. Therefore these register will get reset at RC6
> exit and will start incrementing on next RC6 entry.
> 
> BSpec: 64977
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c |  5 +++++
>   drivers/gpu/drm/i915/gt/intel_gt_regs.h       |  5 +++++
>   drivers/gpu/drm/i915/gt/intel_rc6.c           | 19 +++++++++++++++++++
>   drivers/gpu/drm/i915/gt/intel_rc6.h           |  1 +
>   4 files changed, 30 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
> index 10f680dbd7b62..59b6cc49464e9 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
> @@ -195,6 +195,11 @@ static int gen6_drpc(struct seq_file *m)
>   	print_rc6_res(m, "RC6 \"Locked to RPn\" residency since boot:",
>   		      GEN6_GT_GFX_RC6_LOCKED);
>   	print_rc6_res(m, "RC6 residency since boot:", GEN6_GT_GFX_RC6);
> +
> +	if (GRAPHICS_VER(i915) >= 12)
> +		seq_printf(m, "GT RC6 RPM Unit Residency since last RC6 exit: 0x%llx\n",
> +			   intel_rc6_rpm_unit_residency(&gt->rc6));
> +
>   	print_rc6_res(m, "RC6+ residency since boot:", GEN6_GT_GFX_RC6p);
>   	print_rc6_res(m, "RC6++ residency since boot:", GEN6_GT_GFX_RC6pp);
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> index 7f79bbf978284..7715d0aeffc9d 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> @@ -8,6 +8,11 @@
>   
>   #include "i915_reg_defs.h"
>   
> +/* GT RPM RC6 counter */
> +#define GEN12_GT_GFX_RC6_LSB			_MMIO(0xC20)
> +#define GEN12_GT_GFX_RC6_MSB			_MMIO(0xC24)
> +#define   GEN12_GT_GFX_RC6_MSB_MASK		REG_GENMASK(23, 0)
> +
>   /* RPM unit config (Gen8+) */
>   #define RPM_CONFIG0				_MMIO(0xd00)
>   #define   GEN9_RPM_CONFIG0_CRYSTAL_CLOCK_FREQ_SHIFT	3
> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
> index f8d0523f4c18e..ee830c4027542 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rc6.c
> +++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
> @@ -816,6 +816,25 @@ u64 intel_rc6_residency_us(struct intel_rc6 *rc6, i915_reg_t reg)
>   	return DIV_ROUND_UP_ULL(intel_rc6_residency_ns(rc6, reg), 1000);
>   }
>   
> +u64 intel_rc6_rpm_unit_residency(struct intel_rc6 *rc6)
> +{
> +	struct drm_i915_private *i915 = rc6_to_i915(rc6);
> +	struct intel_gt *gt = rc6_to_gt(rc6);
> +	intel_wakeref_t wakeref;
> +	u64 lsb, msb, counter;
> +
> +	with_intel_runtime_pm(gt->uncore->rpm, wakeref) {
> +		lsb = intel_uncore_read(gt->uncore, GEN12_GT_GFX_RC6_LSB);
> +		msb = intel_uncore_read(gt->uncore, GEN12_GT_GFX_RC6_MSB);
> +	}
> +
> +	drm_dbg(&i915->drm, "GT RC6 MSB=0x%x LSB=0x%x\n", (u32) msb, (u32) lsb);
> +	msb = REG_FIELD_GET(GEN12_GT_GFX_RC6_MSB_MASK, (u32)msb);
> +	counter = msb << 32 | lsb;

What about wrap?

I guess you can't use intel_uncore_read64_2x32 because there is 
something present in bits 31-24?

Anyway, what is the unit here and why it is useful to put this in 
debugfs (together with drm_dbg)? (Considering the value restarts on each 
RC6 entry.)

Regards,

Tvrtko

> +
> +	return counter;
> +}
> +
>   #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>   #include "selftest_rc6.c"
>   #endif
> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.h b/drivers/gpu/drm/i915/gt/intel_rc6.h
> index b6fea71afc223..6fa0896756d47 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rc6.h
> +++ b/drivers/gpu/drm/i915/gt/intel_rc6.h
> @@ -23,5 +23,6 @@ void intel_rc6_disable(struct intel_rc6 *rc6);
>   
>   u64 intel_rc6_residency_ns(struct intel_rc6 *rc6, i915_reg_t reg);
>   u64 intel_rc6_residency_us(struct intel_rc6 *rc6, i915_reg_t reg);
> +u64 intel_rc6_rpm_unit_residency(struct intel_rc6 *rc6);
>   
>   #endif /* INTEL_RC6_H */