Re: [PATCH v7 5/8] drm/i915/lobf: Update lobf if any change in dependent parameters

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Thu, 2025-04-03 at 14:58 +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]
> 
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index aae2c322baa7..7ab29c5fef38 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -360,6 +360,8 @@ static void lnl_alpm_configure(struct intel_dp
> *intel_dp,
>  	if (crtc_state->has_lobf) {
>  		alpm_ctl |= ALPM_CTL_LOBF_ENABLE;
>  		drm_dbg_kms(display->drm, "Link off between frames
> (LOBF) enabled\n");
> +	} else {
> +		drm_dbg_kms(display->drm, "Link off between frames
> (LOBF) disabled\n");
>  	}
>  
>  	alpm_ctl |= ALPM_CTL_ALPM_ENTRY_CHECK(intel_dp-
> >alpm_parameters.check_entry_lines);
> @@ -380,9 +382,12 @@ void intel_alpm_post_plane_update(struct
> intel_atomic_state *state,
>  	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 != old_crtc_state->has_lobf) &&

I usually support artistic freedom... I think here you should really do
 
crtc_state->has_lobf == old_crtc_state->has_lobf

BR,

Jouni Högander


> +	    !crtc_state->has_psr)
>  		return;
>  
>  	for_each_intel_encoder_mask(display->drm, encoder,