On Fri, Mar 08, 2024 at 01:00:36PM +0200, Jouni Högander wrote:
> Current fast and IO wake lines calculation is assuming fast wake sync
> length is 18 pulses. Let's improve this by checking actual length.
>
> Add getter for IO buffer wake time and return 10 us there which was assumed
> with static 42 us IO wake time. Upcoming patches will extent this for
> different display versions.
>
> Bspec: 65450
>
> v3:
> - s/get_io_buffer_wake_time/io_buffer_wake_time/ and use it directly in
> calculation.
> v2:
> - rename io_wake_time in if block to io_buffer_wake_time
> - rename get_io_wake_time to get_io_buffer_wake_time
>
> Signed-off-by: Jouni Högander <jouni.hogander@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_psr.c | 20 ++++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 6927785fd6ff..7736bdcad82d 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1150,6 +1150,11 @@ static bool _lnl_compute_alpm_params(struct intel_dp *intel_dp,
> return true;
> }
>
> +static int io_buffer_wake_time(void)
> +{
> + return 10;
> +}
> +
> static bool _compute_alpm_params(struct intel_dp *intel_dp,
> struct intel_crtc_state *crtc_state)
> {
> @@ -1158,12 +1163,15 @@ static bool _compute_alpm_params(struct intel_dp *intel_dp,
> u8 max_wake_lines;
>
> if (DISPLAY_VER(i915) >= 12) {
> - io_wake_time = 42;
> - /*
> - * According to Bspec it's 42us, but based on testing
> - * it is not enough -> use 45 us.
> - */
> - fast_wake_time = 45;
> + int tfw_exit_latency = 20; /* eDP spec */
> + int phy_wake = 4; /* eDP spec */
> + int preamble = 8; /* eDP spec */
> + int precharge = intel_dp_aux_fw_sync_len() - preamble;
> +
> + io_wake_time = max(precharge, io_buffer_wake_time()) + preamble +
> + 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;
> --
> 2.34.1
--
Ville Syrjälä
Intel
