On Thu, 2025-04-17 at 15:11 +0530, Animesh Manna wrote:
> For every commit the dependent condition for LOBF is checked
> and accordingly update has_lobf flag which will be used
> to update the ALPM_CTL register during commit.
>
> v1: Initial version.
> v2: Avoid reading h/w register without has_lobf check. [Jani]
> v3: Update LOBF in post plane update instead of separate function.
> [Jouni]
> v4:
> - Add lobf disable print. [Jouni]
> - Simplify condition check for enabling/disabling lobf. [Jouni]
> v5: Disable LOBF in pre_plane_update(). [Jouni]
>
> Signed-off-by: Animesh Manna <animesh.ma...@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_alpm.c | 43
> +++++++++++++++++++-
> drivers/gpu/drm/i915/display/intel_alpm.h | 2 +
> drivers/gpu/drm/i915/display/intel_display.c | 1 +
> 3 files changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 01949b90c0c3..3fbe8eca1301 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -376,15 +376,56 @@ void intel_alpm_configure(struct intel_dp
> *intel_dp,
> intel_dp->alpm_parameters.transcoder = crtc_state-
> >cpu_transcoder;
> }
>
> +void intel_alpm_pre_plane_update(struct intel_atomic_state *state,
> + struct intel_crtc *crtc)
> +{
> + struct intel_display *display = to_intel_display(state);
> + const struct intel_crtc_state *crtc_state =
> + intel_atomic_get_new_crtc_state(state, crtc);
> + enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> + struct intel_encoder *encoder;
> + u32 alpm_ctl;
> +
> + if (DISPLAY_VER(display) < 20)
> + return;
> +
> + if (crtc_state->has_lobf)
> + return;
> +
> + for_each_intel_encoder_mask(display->drm, encoder,
> + crtc_state->uapi.encoder_mask) {
> + struct intel_dp *intel_dp;
> +
> + if (!intel_encoder_is_dp(encoder))
> + continue;
> +
> + intel_dp = enc_to_intel_dp(encoder);
> +
> + if (!intel_dp_is_edp(intel_dp))
> + continue;
> +
> + alpm_ctl = intel_de_read(display, ALPM_CTL(display,
> cpu_transcoder));
How about if instead of reading you would rely on old_crtc_state-
>has_lobf as is done in intel_alpm_post_plane_update ? I think you can
write 0 into ALPM_CTL. Parameters are anyways written in
intel_alpm_post_plane_update when ALPM is enable for LOBF or PSR.
BR,
Jouni Högander
> +
> + if (alpm_ctl & ALPM_CTL_LOBF_ENABLE) {
> + alpm_ctl &= ~ALPM_CTL_LOBF_ENABLE;
> + intel_de_write(display, ALPM_CTL(display,
> cpu_transcoder), alpm_ctl);
> + drm_dbg_kms(display->drm, "Link off between
> frames (LOBF) disabled\n");
> + }
> + }
> +}
> +
> void intel_alpm_post_plane_update(struct intel_atomic_state *state,
> struct intel_crtc *crtc)
> {
> struct intel_display *display = to_intel_display(state);
> const struct intel_crtc_state *crtc_state =
> intel_atomic_get_new_crtc_state(state, crtc);
> + const struct intel_crtc_state *old_crtc_state =
> + intel_atomic_get_old_crtc_state(state, crtc);
> struct intel_encoder *encoder;
>
> - if (!crtc_state->has_lobf && !crtc_state->has_psr)
> + if ((!crtc_state->has_lobf ||
> + crtc_state->has_lobf == old_crtc_state->has_lobf) &&
> !crtc_state->has_psr)
> return;
>
> for_each_intel_encoder_mask(display->drm, encoder,
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.h
> b/drivers/gpu/drm/i915/display/intel_alpm.h
> index 91f51fb24f98..77bae022a0ea 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.h
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.h
> @@ -23,6 +23,8 @@ void intel_alpm_lobf_compute_config(struct intel_dp
> *intel_dp,
> struct drm_connector_state
> *conn_state);
> void intel_alpm_configure(struct intel_dp *intel_dp,
> const struct intel_crtc_state
> *crtc_state);
> +void intel_alpm_pre_plane_update(struct intel_atomic_state *state,
> + struct intel_crtc *crtc);
> void intel_alpm_post_plane_update(struct intel_atomic_state *state,
> struct intel_crtc *crtc);
> void intel_alpm_lobf_debugfs_add(struct intel_connector *connector);
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> b/drivers/gpu/drm/i915/display/intel_display.c
> index 96a95bc9d5bf..f91401ebdd1a 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -1177,6 +1177,7 @@ static void intel_pre_plane_update(struct
> intel_atomic_state *state,
> intel_atomic_get_new_crtc_state(state, crtc);
> enum pipe pipe = crtc->pipe;
>
> + intel_alpm_pre_plane_update(state, crtc);
> intel_psr_pre_plane_update(state, crtc);
>
> if (intel_crtc_vrr_disabling(state, crtc)) {
