Re: [PATCH] drm/i915/alpm: Remove error handling from get_lfps_cycle_min_max_time

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Mon, 2025-09-15 at 15:03 +0000, Kahola, Mika wrote:
> > -----Original Message-----
> > From: Intel-xe <intel-xe-bounces@lists.freedesktop.org> On Behalf
> > Of Jouni Högander
> > Sent: Friday, 12 September 2025 9.41
> > To: intel-xe@lists.freedesktop.org; intel-gfx@lists.freedesktop.org
> > Cc: Hogander, Jouni <jouni.hogander@intel.com>
> > Subject: [PATCH] drm/i915/alpm: Remove error handling from
> > get_lfps_cycle_min_max_time
> > 
> > Getter for LFPS cycle min/max times is unnecessarily checking
> > faulty port clock value. This doesn't make sense as erroneous port
> > clock value would have been noticed already at this point. Remove
> > this check and use 140/800 ns always when port clock >
> > 540000.
> > 
> 
> Reviewed-by: Mika Kahola <mika.kahola@intel.com>

Thank you Mika for checking my patch. This is now pushed to drm-intel-
next.

BR,

Jouni Högander

> 
> > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_alpm.c | 29 +++++++------------
> > ----
> >  1 file changed, 8 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> > b/drivers/gpu/drm/i915/display/intel_alpm.c
> > index ed7a7ed486b5..749119cc0b28 100644
> > --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> > +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> > @@ -58,43 +58,32 @@ static int get_silence_period_symbols(const
> > struct intel_crtc_state *crtc_state)
> >  		1000 / 1000;
> >  }
> > 
> > -static int get_lfps_cycle_min_max_time(const struct
> > intel_crtc_state *crtc_state,
> > -				       int *min, int *max)
> > +static void get_lfps_cycle_min_max_time(const struct
> > intel_crtc_state *crtc_state,
> > +					int *min, int *max)
> >  {
> >  	if (crtc_state->port_clock < 540000) {
> >  		*min = 65 * LFPS_CYCLE_COUNT;
> >  		*max = 75 * LFPS_CYCLE_COUNT;
> > -	} else if (crtc_state->port_clock <= 810000) {
> > +	} else {
> >  		*min = 140;
> >  		*max = 800;
> > -	} else {
> > -		*min = *max = -1;
> > -		return -1;
> >  	}
> > -
> > -	return 0;
> >  }
> > 
> >  static int get_lfps_cycle_time(const struct intel_crtc_state
> > *crtc_state)  {
> > -	int tlfps_cycle_min, tlfps_cycle_max, ret;
> > +	int tlfps_cycle_min, tlfps_cycle_max;
> > 
> > -	ret = get_lfps_cycle_min_max_time(crtc_state,
> > &tlfps_cycle_min,
> > -					  &tlfps_cycle_max);
> > -	if (ret)
> > -		return ret;
> > +	get_lfps_cycle_min_max_time(crtc_state, &tlfps_cycle_min,
> > +				    &tlfps_cycle_max);
> > 
> >  	return tlfps_cycle_min +  (tlfps_cycle_max -
> > tlfps_cycle_min) / 2;  }
> > 
> >  static int get_lfps_half_cycle_clocks(const struct
> > intel_crtc_state *crtc_state)  {
> > -	int lfps_cycle_time = get_lfps_cycle_time(crtc_state);
> > -
> > -	if (lfps_cycle_time < 0)
> > -		return -1;
> > -
> > -	return lfps_cycle_time * crtc_state->port_clock / 1000 /
> > 1000 / (2 * LFPS_CYCLE_COUNT);
> > +	return get_lfps_cycle_time(crtc_state) * crtc_state-
> > >port_clock / 1000 /
> > +		1000 / (2 * LFPS_CYCLE_COUNT);
> >  }
> > 
> >  /*
> > @@ -146,8 +135,6 @@ _lnl_compute_aux_less_alpm_params(struct
> > intel_dp *intel_dp,
> >  	silence_period = get_silence_period_symbols(crtc_state);
> > 
> >  	lfps_half_cycle = get_lfps_half_cycle_clocks(crtc_state);
> > -	if (lfps_half_cycle < 0)
> > -		return false;
> > 
> >  	if (aux_less_wake_lines > ALPM_CTL_AUX_LESS_WAKE_TIME_MASK
> > ||
> >  	    silence_period > PORT_ALPM_CTL_SILENCE_PERIOD_MASK ||
> > --
> > 2.43.0
>