On Thu, 23 Oct 2025, Animesh Manna <[email protected]> wrote:
> Add support for auxless waketime calculation for DP2.1 ALPM
> as dependent parameter got changed.
>
> Cc: Jouni Högander <[email protected]>
> Signed-off-by: Animesh Manna <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_alpm.c | 78 +++++++++++++++++++----
> 1 file changed, 67 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 0f6b15bca3be..ee5b1e3d79d2 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -96,6 +96,66 @@ static int get_lfps_half_cycle_clocks(const struct
> intel_crtc_state *crtc_state)
> 1000 / (2 * LFPS_CYCLE_COUNT);
> }
>
> +static int get_tphy2_p2_to_p0(struct intel_dp *intel_dp)
> +{
> + struct intel_display *display = to_intel_display(intel_dp);
> +
> + return DISPLAY_VER(display) >= 35 ? (40 * 1000) : (12 * 1000);
> +}
> +
> +static int get_establishment_period(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state)
> +{
> + int port_clock = crtc_state->port_clock;
> + int t1 = 50 * 1000;
> + int tps4 = (port_clock >= 1000000) ? (396 * 32) : (252 * 10);
intel_dp_is_uhbr()
> + int tml_phy_lock = 1000 * 1000 * tps4 / port_clock / 10;
That would overflow 32 bits.
> + int lttpr_count = 0;
> + int establishment_period;
> + int tcds;
> +
> + if (!intel_dp_is_edp(intel_dp)) {
Please turn the branches around to not have the !.
> + lttpr_count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps);
> + tcds = 7 * tml_phy_lock;
> + } else {
> + tcds = (7 + DIV_ROUND_UP(6500, tml_phy_lock) + 1) *
> tml_phy_lock;
> + }
> +
> + if (lttpr_count) {
> + int tlw = 13000;
> + int tcs = 10000;
> + int tlfps_period = get_lfps_cycle_time(crtc_state);
> + int tdcs = (SILENCE_PERIOD_TIME + t1 + tcs +
> + (lttpr_count - 1) * (tlw + tlfps_period));
> + int tacds = 70000;
> + int tds = (lttpr_count - 1) * 7 * tml_phy_lock;
> +
> + /* tdrl is same as tcds*/
> + establishment_period = tlw + tlfps_period + tdcs + tacds + tds
> + tcds;
> + } else {
> + /* TODO: Add a check for data realign by DPCD 0x116[3] */
> +
> + establishment_period = (SILENCE_PERIOD_TIME + t1 + tcds);
> + }
> +
> + return establishment_period;
> +}
> +
> +static int get_switch_to_active(int port_clock)
> +{
> + int switch_to_active;
> +
> + if (port_clock >= 1000000) {
Again, there are uhbr helpers.
> + int symbol_clock = port_clock /
> intel_dp_link_symbol_size(port_clock);
> +
> + switch_to_active = 32 * DIV_ROUND_UP((396 + 3 + 64),
> symbol_clock);
> + } else {
> + switch_to_active = 0;
> + }
> +
> + return switch_to_active;
> +}
> +
> /*
> * AUX-Less Wake Time = CEILING( ((PHY P2 to P0) + tLFPS_Period, Max+
> * tSilence, Max+ tPHY Establishment + tCDS) / tline)
> @@ -115,19 +175,15 @@ static int get_lfps_half_cycle_clocks(const struct
> intel_crtc_state *crtc_state)
> * tML_PHY_LOCK = TPS4 Length * ( 10 / (Link Rate in MHz) )
> * TPS4 Length = 252 Symbols
> */
> -static int _lnl_compute_aux_less_wake_time(const struct intel_crtc_state
> *crtc_state)
> +static int _lnl_compute_aux_less_wake_time(struct intel_dp *intel_dp,
> + const struct intel_crtc_state
> *crtc_state)
> {
> - int tphy2_p2_to_p0 = 12 * 1000;
> - int t1 = 50 * 1000;
> - int tps4 = 252;
> - /* port_clock is link rate in 10kbit/s units */
> - int tml_phy_lock = 1000 * 1000 * tps4 / crtc_state->port_clock;
> - int num_ml_phy_lock = 7 + DIV_ROUND_UP(6500, tml_phy_lock) + 1;
> - int t2 = num_ml_phy_lock * tml_phy_lock;
> - int tcds = 1 * t2;
> + int tphy2_p2_to_p0 = get_tphy2_p2_to_p0(intel_dp);
> + int establishment_period = get_establishment_period(intel_dp,
> crtc_state);
> + int switch_to_active = get_switch_to_active(crtc_state->port_clock);
>
> return DIV_ROUND_UP(tphy2_p2_to_p0 + get_lfps_cycle_time(crtc_state) +
> - SILENCE_PERIOD_TIME + t1 + tcds, 1000);
> + establishment_period + switch_to_active, 1000);
Looks like you should *first* refactor this to separate functions,
before adding functionality.
> }
>
> static int
> @@ -139,7 +195,7 @@ _lnl_compute_aux_less_alpm_params(struct intel_dp
> *intel_dp,
> lfps_half_cycle;
>
> aux_less_wake_time =
> - _lnl_compute_aux_less_wake_time(crtc_state);
> + _lnl_compute_aux_less_wake_time(intel_dp, crtc_state);
> aux_less_wake_lines =
> intel_usecs_to_scanlines(&crtc_state->hw.adjusted_mode,
> aux_less_wake_time);
> silence_period = get_silence_period_symbols(crtc_state);
--
Jani Nikula, Intel
