On Wed, Mar 06, 2024 at 10:34:25AM +0200, Jouni Högander wrote: > Bspec mentions 50 us for IO wake time and 32 us for fast wake time. 32 us > is most probably wrong as it doesn't meet the specification as fast wake > time is calculated in Bspec like this: > > 10..16 us (precharge) + 8 us (preamble) + 4 us (phy_wake) + 20 us > (tfw_exit_latency) > > Instead of using these constants calculate IO wake and fast wake for > DISPLAY_VER < 12 as well. > > v2: > - initialize io/fast_wake_time for display version < 9 > > Signed-off-by: Jouni Högander <[email protected]> > --- > drivers/gpu/drm/i915/display/intel_psr.c | 34 ++++++++++++++++++------ > 1 file changed, 26 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c > b/drivers/gpu/drm/i915/display/intel_psr.c > index 905208e1c771..e1df0ece9fa3 100644 > --- a/drivers/gpu/drm/i915/display/intel_psr.c > +++ b/drivers/gpu/drm/i915/display/intel_psr.c > @@ -1150,9 +1150,25 @@ static bool _lnl_compute_alpm_params(struct intel_dp > *intel_dp, > return true; > } > > -static int get_io_buffer_wake_time(void) > +/* > + * From Bspec: > + * > + * For DISPLAY_VER >= 12 > + * 10 us > + * > + * For DISPLAY_VER < 12 > + * This is not directly mentioned in Bspec. There are 50 us io wake time and > 32 > + * us fast wake time. Clearly preharge pulses are not (improperly) included > in > + * 32 us fast wake time. 50 us - 32 us = 18 us. > + */ > +static int get_io_buffer_wake_time(const struct intel_crtc_state *crtc_state) > { > - return 10; > + struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev); > + > + if (DISPLAY_VER(i915) < 12) > + return 18; > + else > + return 10; > } > > static bool _compute_alpm_params(struct intel_dp *intel_dp, > @@ -1162,8 +1178,8 @@ static bool _compute_alpm_params(struct intel_dp > *intel_dp, > int io_wake_lines, io_wake_time, fast_wake_lines, fast_wake_time; > u8 max_wake_lines; > > - if (DISPLAY_VER(i915) >= 12) { > - int io_buffer_wake_time = get_io_buffer_wake_time(); > + if (DISPLAY_VER(i915) >= 9) { > + int io_buffer_wake_time = get_io_buffer_wake_time(crtc_state); > int tfw_exit_latency = 20; /* eDP spec */ > int phy_wake = 4; /* eDP spec */ > int preamble = 8; /* eDP spec */ > @@ -1173,15 +1189,17 @@ static bool _compute_alpm_params(struct intel_dp > *intel_dp, > phy_wake + tfw_exit_latency; > fast_wake_time = precharge + preamble + phy_wake + > tfw_exit_latency; > - > - /* TODO: Check how we can use ALPM_CTL fast wake extended field > */ > - max_wake_lines = 12; > } else { > io_wake_time = 50; > fast_wake_time = 32; > - max_wake_lines = 8;
Isn't the whole else branch dead code now? > } > > + if (DISPLAY_VER(i915) >= 12) > + /* TODO: Check how we can use ALPM_CTL fast wake extended field > */ > + max_wake_lines = 12; > + else > + max_wake_lines = 8; > + > io_wake_lines = intel_usecs_to_scanlines( > &crtc_state->hw.adjusted_mode, io_wake_time); > fast_wake_lines = intel_usecs_to_scanlines( > -- > 2.34.1 -- Ville Syrjälä Intel
