Re: [PATCH v6 7/8] drm/i915/lobf: Add mutex for alpm update

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

On Thu, 2025-03-20 at 00:45 +0530, Animesh Manna wrote:
> The ALPM_CTL can be updated from different context, so
> add mutex to sychonize the update.

This patch 7 and 6 should be vice versa. Otherwise this looks ok:

Reviewed-by: Jouni Högander <jouni.hogander@intel.com> 
> 
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c          | 9 ++++++++-
>  drivers/gpu/drm/i915/display/intel_alpm.h          | 2 +-
>  drivers/gpu/drm/i915/display/intel_display_types.h | 1 +
>  drivers/gpu/drm/i915/display/intel_dp.c            | 2 +-
>  4 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 562f7269a583..b44aeef390a6 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -23,7 +23,7 @@ bool intel_alpm_aux_less_wake_supported(struct
> intel_dp *intel_dp)
>  	return intel_dp->alpm_dpcd & DP_ALPM_AUX_LESS_CAP;
>  }
>  
> -void intel_alpm_init_dpcd(struct intel_dp *intel_dp)
> +void intel_alpm_init(struct intel_dp *intel_dp)
>  {
>  	u8 dpcd;
>  
> @@ -31,6 +31,7 @@ void intel_alpm_init_dpcd(struct intel_dp
> *intel_dp)
>  		return;
>  
>  	intel_dp->alpm_dpcd = dpcd;
> +	mutex_init(&intel_dp->alpm_parameters.lock);
>  }
>  
>  /*
> @@ -327,6 +328,7 @@ static void lnl_alpm_configure(struct intel_dp
> *intel_dp,
>  	    (!intel_dp->psr.sel_update_enabled &&
> !intel_dp_is_edp(intel_dp)))
>  		return;
>  
> +	mutex_lock(&intel_dp->alpm_parameters.lock);
>  	/*
>  	 * Panel Replay on eDP is always using ALPM aux less. I.e.
> no need to
>  	 * check panel support at this point.
> @@ -366,6 +368,7 @@ static void lnl_alpm_configure(struct intel_dp
> *intel_dp,
>  	alpm_ctl |= ALPM_CTL_ALPM_ENTRY_CHECK(intel_dp-
> >alpm_parameters.check_entry_lines);
>  
>  	intel_de_write(display, ALPM_CTL(display, cpu_transcoder),
> alpm_ctl);
> +	mutex_unlock(&intel_dp->alpm_parameters.lock);
>  }
>  
>  void intel_alpm_configure(struct intel_dp *intel_dp,
> @@ -489,6 +492,8 @@ void intel_alpm_disable(struct intel_dp
> *intel_dp)
>  	if (DISPLAY_VER(display) < 20)
>  		return;
>  
> +	mutex_lock(&intel_dp->alpm_parameters.lock);
> +
>  	intel_de_rmw(display, ALPM_CTL(display, cpu_transcoder),
>  		     ALPM_CTL_ALPM_ENABLE | ALPM_CTL_LOBF_ENABLE |
>  		     ALPM_CTL_ALPM_AUX_LESS_ENABLE, 0);
> @@ -498,6 +503,8 @@ void intel_alpm_disable(struct intel_dp
> *intel_dp)
>  		     PORT_ALPM_CTL_ALPM_AUX_LESS_ENABLE, 0);
>  
>  	drm_dbg_kms(display->drm, "Disabling ALPM\n");
> +
> +	mutex_unlock(&intel_dp->alpm_parameters.lock);
>  }
>  
>  bool intel_alpm_get_error(struct intel_dp *intel_dp)
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.h
> b/drivers/gpu/drm/i915/display/intel_alpm.h
> index 2f1fb82c0aac..4f86322a9995 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.h
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.h
> @@ -15,7 +15,7 @@ struct intel_connector;
>  struct intel_atomic_state;
>  struct intel_crtc;
>  
> -void intel_alpm_init_dpcd(struct intel_dp *intel_dp);
> +void intel_alpm_init(struct intel_dp *intel_dp);
>  bool intel_alpm_compute_params(struct intel_dp *intel_dp,
>  			       const struct intel_crtc_state
> *crtc_state);
>  void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp,
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 0b109aac5306..6b8fb0dff1ea 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1806,6 +1806,7 @@ struct intel_dp {
>  		u8 io_wake_lines;
>  		u8 fast_wake_lines;
>  		enum transcoder transcoder;
> +		struct mutex lock;
>  
>  		/* LNL and beyond */
>  		u8 check_entry_lines;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 3f0fa2238afa..4e4e1dba0f2e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -6362,7 +6362,7 @@ static bool intel_edp_init_connector(struct
> intel_dp *intel_dp,
>  	 */
>  	intel_hpd_enable_detection(encoder);
>  
> -	intel_alpm_init_dpcd(intel_dp);
> +	intel_alpm_init(intel_dp);
>  
>  	/* Cache DPCD and EDID for edp. */
>  	has_dpcd = intel_edp_init_dpcd(intel_dp, connector);