> Subject: [PATCH v4 05/10] drm/i915/alpm: Auxless wake time calculation for
> Xe3p
> 
> Add support for auxless waketime calculation for DP2.1 ALPM as dependent
> parameter got changed.
> 
> v1: Initial version.
> v2: Use intel_dp_is_uhbr(). [Jani]
> 

Add Bspec no. here

> Cc: Jouni Högander <[email protected]>
> Signed-off-by: Animesh Manna <[email protected]>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c | 63 +++++++++++++++++++----
>  1 file changed, 53 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index b4b874dd3725..81472254ab73 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -100,23 +100,64 @@ static int get_lfps_half_cycle_clocks(const struct
> intel_crtc_state *crtc_state)
> 
>  static int get_tphy2_p2_to_p0(const struct intel_crtc_state *crtc_state)  {
> -     return 12 * 1000;
> +     struct intel_display *display = to_intel_display(crtc_state);
> +
> +     return DISPLAY_VER(display) >= 35 ? (40 * 1000) : (12 * 1000);
>  }
> 
> -static int get_establishment_period(const struct intel_crtc_state 
> *crtc_state)
> +static int get_establishment_period(struct intel_dp *intel_dp,
> +                                 const struct intel_crtc_state *crtc_state)
>  {
>       int t1 = 50 * 1000;
> -     int tps4 = 252;
> +     int tps4 = intel_dp_is_uhbr(crtc_state) ? (396 * 32) : (252 * 10);
>       /* port_clock is link rate in 10kbit/s units */
> -     int tml_phy_lock = 1000 * 1000 * tps4 / crtc_state->port_clock;
> +     int tml_phy_lock = 1000 * 1000 * tps4 / crtc_state->port_clock / 10;
> +     int lttpr_count = 0;
>       int tcds, establishment_period;
> 
> -     tcds = (7 + DIV_ROUND_UP(6500, tml_phy_lock) + 1) * tml_phy_lock;
> -     establishment_period = (SILENCE_PERIOD_TIME + t1 + tcds);
> +     if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_EDP)) {
> +             tcds = (7 + DIV_ROUND_UP(6500, tml_phy_lock) + 1) *
> tml_phy_lock;
> +     } else {
> +             tcds = 7 * tml_phy_lock;
> +             lttpr_count = drm_dp_lttpr_count(intel_dp-
> >lttpr_common_caps);
> +     }
> +
> +     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(const struct intel_crtc_state
> +*crtc_state) {
> +     int port_clock = crtc_state->port_clock;
> +     int switch_to_active;

Make this switch_to_active = 0 that way the else block later is not required 

> +
> +     if (intel_dp_is_uhbr(crtc_state)) {
> +             int symbol_clock = port_clock /
> +intel_dp_link_symbol_size(port_clock);
> +
> +             switch_to_active = 32 * DIV_ROUND_UP((396 + 3 + 64),

I would like if you had 396 assigned as a variable ml_phy_lock_len

> symbol_clock);
> +     } else {
> +             switch_to_active = 0;
> +     }

Should you not take care of  the mst use case.

So the switch to active latency seems wrong here what you are calculating here 
is
T_switch_to_active = 32 * DIV_ROUND_UP((396 + 3 + 64),flink)
Switch_to_active_latency= CEIL(t_switch_to_active/t_line)
And this need to be written to ALPM_CTL2 which you are not doing see below 
comment.
Also you are not taking into account the fact that f_link is in MHZ and 
intel_dp_link_symbol_clock give value in kHZ so probably look into that too.
Still not sure how f_link is the intel_dp_link_symbol_clock can you explain 
that too?

> +
> +     return switch_to_active;
> +}
> +
>  /*
>   * AUX-Less Wake Time = CEILING( ((PHY P2 to P0) + tLFPS_Period, Max+
>   * tSilence, Max+ tPHY Establishment + tCDS) / tline) @@ -136,13 +177,15
> @@ static int get_establishment_period(const struct intel_crtc_state
> *crtc_state)
>   * tML_PHY_LOCK = TPS4 Length * ( 10 / (Link Rate in MHz) )
>   * TPS4 Length = 252 Symbols
>   */

Lot of changes in this function and how we calculate data so the comment also 
needs to change here
To reflect those changes.


> -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 = get_tphy2_p2_to_p0(crtc_state);
> -     int establishment_period = get_establishment_period(crtc_state);
> +     int establishment_period = get_establishment_period(intel_dp,
> crtc_state);
> +     int switch_to_active = get_switch_to_active(crtc_state);
> 
>       return DIV_ROUND_UP(tphy2_p2_to_p0 +
> get_lfps_cycle_time(crtc_state) +
> -                         establishment_period, 1000);
> +                         establishment_period + switch_to_active, 1000);

I do not think you have to  add the switch to active latency here,
Switch to active latency a separate field in ALPM_CTL2 so you will have to 
write it
Which means you need to create another variable that you fill with switch to 
active latency.
H/w will internally maintain Aux Wake time + Switch to active latency.
I don't see you writing to ALPM_CTL2[Switch to Active time] here or anywhere 
else did you miss it?

Regards,
Suraj Kandpal

>  }
> 
>  static int
> @@ -154,7 +197,7 @@ _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);
> --
> 2.29.0

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