Re: [PATCH v5 08/15] drm/i915/alpm: Half LFPS cycle calculation

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

On Wed, 2026-09-02 at 11:41 +0300, Hogander, Jouni wrote:
> On Tue, 2026-08-25 at 11:15 +0530, Animesh Manna wrote:
> > Add support for half LFPS cycle calculation for DP2.1 ALPM as
> > dependent
> > parameters got changed.
> > 
> > v1: Initial version.
> > v2: Avoid returning early. [Jani]
> > v3: Use intel_crtc_has_type(). [Suraj]
> > 
> > Cc: Jouni Högander <jouni.hogander@intel.com>
> > Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_alpm.c | 18 ++++++++++++------
> >  1 file changed, 12 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> > b/drivers/gpu/drm/i915/display/intel_alpm.c
> > index 078e04bb69d2..98aa418a6ff7 100644
> > --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> > +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> > @@ -80,12 +80,18 @@ static int get_silence_period_symbols(const
> > struct intel_crtc_state *crtc_state)
> >  static void get_lfps_cycle_min_max_time(const struct
> > intel_crtc_state *crtc_state,
> 
> Not your patch, but maybe better naming would be
> get_lfps_period_min_max_time()
> 
> >  					int *min, int *max)
> >  {
> > -	if (crtc_state->port_clock < 540000) {
> > -		*min = 65 * LFPS_CYCLE_COUNT;
> > -		*max = 75 * LFPS_CYCLE_COUNT;
> > -	} else {
> > -		*min = 140;
> > -		*max = 800;
> > +	struct intel_display *display =
> > to_intel_display(crtc_state);
> > +
> > +	*min = 320;
> > +	*max = 1600;
> > +	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_EDP)) {
> > +		if (crtc_state->port_clock < 540000 &&
> > DISPLAY_VER(display) < 35) {
> > +			*min = 65 * LFPS_CYCLE_COUNT;
> > +			*max = 75 * LFPS_CYCLE_COUNT;
> > +		} else {
> > +			*min = 140;
> > +			*max = 800;
> > +		}
> 
> This is getting messy. Maybe it would be more clear to have:
> 
> if (DISPLAY_VER(display) < 35)
>     get_lfps_cycle_min_max_time_cx0()
> else
>     get_lfps_cycle_min_max_time_lt()

HAS_LT_PHY(display) would be better to use than display version.

BR,
Jouni Högander

> 
> BR,
> Jouni Högander
> >  	}
> >  }
> >  
>