> -----Original Message-----
> From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Jouni
> Högander
> Sent: Wednesday, August 13, 2025 12:36 PM
> To: intel-gfx@lists.freedesktop.org; intel...@lists.freedesktop.org
> Cc: Hogander, Jouni <jouni.hogan...@intel.com>
> Subject: [PATCH 1/4] drm/i915/alpm: Calculate silence period
>
> Calculate silence period instead of hardcoding it in switch case.
>
> Signed-off-by: Jouni Högander <jouni.hogan...@intel.com>
LGTM.
Reviewed-by: Animesh Manna <animesh.ma...@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_alpm.c | 37 +++++++++++------------
> 1 file changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index dfdde8e4eabe..e48a4218c163 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -16,6 +16,12 @@
> #include "intel_psr.h"
> #include "intel_psr_regs.h"
>
> +#define SILENCE_PERIOD_MIN_TIME 80
> +#define SILENCE_PERIOD_MAX_TIME 180
> +#define SILENCE_PERIOD_TIME (SILENCE_PERIOD_MIN_TIME + \
> + (SILENCE_PERIOD_MAX_TIME - \
> + SILENCE_PERIOD_MIN_TIME) / 2)
> +
> bool intel_alpm_aux_wake_supported(struct intel_dp *intel_dp) {
> return intel_dp->alpm_dpcd & DP_ALPM_CAP; @@ -44,11 +50,15
> @@ void intel_alpm_init(struct intel_dp *intel_dp)
> mutex_init(&intel_dp->alpm_parameters.lock);
> }
>
> +static int get_silence_period_symbols(const struct intel_crtc_state
> +*crtc_state) {
> + return SILENCE_PERIOD_TIME *
> intel_dp_link_symbol_clock(crtc_state->port_clock) /
> + 1000 / 1000;
> +}
> +
> /*
> * See Bspec: 71632 for the table
> *
> - * Silence_period = tSilence,Min + ((tSilence,Max - tSilence,Min) / 2)
> - *
> * Half cycle duration:
> *
> * Link rates 1.62 - 4.32 and tLFPS_Cycle = 70 ns @@ -60,53 +70,41 @@ void
> intel_alpm_init(struct intel_dp *intel_dp)
> * FLOOR( LFPS Period in Symbol clocks /
> * (2 * PORT_ALPM_LFPS_CTL[ LFPS Cycle Count ]) )
> */
> -static bool _lnl_get_silence_period_and_lfps_half_cycle(int link_rate,
> - int *silence_period,
> - int *lfps_half_cycle)
> +static bool _lnl_get_lfps_half_cycle(int link_rate, int
> +*lfps_half_cycle)
> {
> switch (link_rate) {
> case 162000:
> - *silence_period = 20;
> *lfps_half_cycle = 5;
> break;
> case 216000:
> - *silence_period = 27;
> *lfps_half_cycle = 7;
> break;
> case 243000:
> - *silence_period = 31;
> *lfps_half_cycle = 8;
> break;
> case 270000:
> - *silence_period = 34;
> *lfps_half_cycle = 9;
> break;
> case 324000:
> - *silence_period = 41;
> *lfps_half_cycle = 11;
> break;
> case 432000:
> - *silence_period = 56;
> *lfps_half_cycle = 15;
> break;
> case 540000:
> - *silence_period = 69;
> *lfps_half_cycle = 12;
> break;
> case 648000:
> - *silence_period = 84;
> *lfps_half_cycle = 15;
> break;
> case 675000:
> - *silence_period = 87;
> *lfps_half_cycle = 15;
> break;
> case 810000:
> - *silence_period = 104;
> *lfps_half_cycle = 19;
> break;
> default:
> - *silence_period = *lfps_half_cycle = -1;
> + *lfps_half_cycle = -1;
> return false;
> }
> return true;
> @@ -160,10 +158,9 @@ _lnl_compute_aux_less_alpm_params(struct
> intel_dp *intel_dp,
> _lnl_compute_aux_less_wake_time(crtc_state->port_clock);
> aux_less_wake_lines = intel_usecs_to_scanlines(&crtc_state-
> >hw.adjusted_mode,
> aux_less_wake_time);
> -
> - if (!_lnl_get_silence_period_and_lfps_half_cycle(crtc_state-
> >port_clock,
> - &silence_period,
> - &lfps_half_cycle))
> + silence_period = get_silence_period_symbols(crtc_state);
> + if (!_lnl_get_lfps_half_cycle(crtc_state->port_clock,
> + &lfps_half_cycle))
> return false;
>
> if (aux_less_wake_lines > ALPM_CTL_AUX_LESS_WAKE_TIME_MASK
> ||
> --
> 2.43.0
