Re: [Intel-gfx] [PATCH 6/6] drm/i915/rps: Freq caps for MTL

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Mon, 05 Sep 2022 02:40:08 -0700, Jani Nikula wrote:
> On Fri, 02 Sep 2022, Ashutosh Dixit <ashutosh.dixit@intel.com> wrote:
> > For MTL, when reading from HW, RP0, RP1 (actuall RPe) and RPn freq use an
> > entirely different set of registers with different fields, bitwidths and
> > units.
> >
> > Cc: Badal Nilawar <badal.nilawar@intel.com>
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> > ---
> >  drivers/gpu/drm/i915/gt/intel_rps.c | 20 ++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_reg.h     |  9 +++++++++
> >  2 files changed, 29 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c b/drivers/gpu/drm/i915/gt/intel_rps.c
> > index 579ae9ac089c..e7ab172698e3 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_rps.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_rps.c
> > @@ -1085,6 +1085,23 @@ static u32 intel_rps_read_state_cap(struct intel_rps *rps)
> >		return intel_uncore_read(uncore, GEN6_RP_STATE_CAP);
> >  }
> >
> > +static void
> > +mtl_get_freq_caps(struct intel_rps *rps, struct intel_rps_freq_caps *caps)
> > +{
> > +	struct intel_uncore *uncore = rps_to_uncore(rps);
> > +	u32 rp_state_cap = rps_to_gt(rps)->type == GT_MEDIA ?
> > +				intel_uncore_read(uncore, MTL_MEDIAP_STATE_CAP) :
> > +				intel_uncore_read(uncore, MTL_RP_STATE_CAP);
> > +	u32 rpe = rps_to_gt(rps)->type == GT_MEDIA ?
> > +			intel_uncore_read(uncore, MTL_MPE_FREQUENCY) :
> > +			intel_uncore_read(uncore, MTL_GT_RPE_FREQUENCY);
> > +
> > +	/* MTL values are in units of 16.67 MHz */
> > +	caps->rp0_freq = REG_FIELD_GET(MTL_RP0_CAP_MASK, rp_state_cap);
> > +	caps->min_freq = REG_FIELD_GET(MTL_RPN_CAP_MASK, rp_state_cap);
> > +	caps->rp1_freq = REG_FIELD_GET(MTL_RPE_MASK, rpe);
> > +}
> > +
> >  /**
> >   * gen6_rps_get_freq_caps - Get freq caps exposed by HW
> >   * @rps: the intel_rps structure
> > @@ -1098,6 +1115,9 @@ void gen6_rps_get_freq_caps(struct intel_rps *rps, struct intel_rps_freq_caps *c
> >	struct drm_i915_private *i915 = rps_to_i915(rps);
> >	u32 rp_state_cap;
> >
> > +	if (IS_METEORLAKE(i915))
> > +		return mtl_get_freq_caps(rps, caps);
> > +
>
> Please make gen6_rps_get_freq_caps() static, and add
>
> intel_rps_get_freq_caps()
> {
>	if (IS_METEORLAKE(i915))
>		return mtl_get_freq_caps(rps, caps);
>	else
>		return gen6_rps_get_freq_caps(rps, caps);
> }
>
> Or something.

A general name like intel_rps_get_freq_caps name does not sit well with the
current code. intel_rps_get_freq_caps was actually used in earlier versions
of the patch:

https://patchwork.freedesktop.org/patch/479179/?series=101606&rev=3

but was later changed to gen6_rps_get_freq_caps based on review
comments. Afaiu in i915 a name such as gen6_rps_get_freq_caps implies "Gen6
and later" and the gen6_rps_get_freq_caps name has actually proved quite
useful in reminding people that there are earlier/other generations not
covered by the function. See intel_rps_init.

Further the call stack is:

intel_rps_init -> gen6_rps_init -> gen6_rps_get_freq_caps

So it would look odd if we called intel_rps_get_freq_caps from
gen6_rps_init.

Therefore what I have done in v2 is:

s/gen6_rps_get_freq_caps/__gen6_rps_get_freq_caps/

and then

gen6_rps_get_freq_caps()
{
	if (IS_METEORLAKE(i915))
		return mtl_get_freq_caps(rps, caps);
	else
		return __gen6_rps_get_freq_caps(rps, caps);
}

Thanks.
--
Ashutosh

> >	rp_state_cap = intel_rps_read_state_cap(rps);
> >
> >	/* static values from HW: RP0 > RP1 > RPn (min_freq) */
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 06d555321651..d78f9675aa57 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -1792,6 +1792,15 @@
> >  #define XEHPSDV_RP_STATE_CAP	_MMIO(0x250014)
> >  #define PVC_RP_STATE_CAP	_MMIO(0x281014)
> >
> > +#define MTL_RP_STATE_CAP	_MMIO(0x138000)
> > +#define MTL_MEDIAP_STATE_CAP	_MMIO(0x138020)
> > +#define   MTL_RP0_CAP_MASK	REG_GENMASK(8, 0)
> > +#define   MTL_RPN_CAP_MASK	REG_GENMASK(24, 16)
> > +
> > +#define MTL_GT_RPE_FREQUENCY	_MMIO(0x13800c)
> > +#define MTL_MPE_FREQUENCY	_MMIO(0x13802c)
> > +#define   MTL_RPE_MASK		REG_GENMASK(8, 0)
> > +
> >  #define GT0_PERF_LIMIT_REASONS		_MMIO(0x1381a8)
> >  #define   GT0_PERF_LIMIT_REASONS_MASK	0xde3
> >  #define   PROCHOT_MASK			REG_BIT(1)
>
> --
> Jani Nikula, Intel Open Source Graphics Center