Re: [PATCH v7 1/3] drm/i915/display: Add drm helper to check pr optimization support

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

On Thu, 2026-03-12 at 10:30 +0530, Animesh Manna wrote:
> Add api to check panel replay optimization supported or not to
> drm-core DP tunneling framework which can be used by other driver
> as well.
> 
> Suggested-by: Imre Deak <imre.deak@intel.com>
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/display/drm_dp_tunnel.c        | 17
> +++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp_tunnel.c | 14 ++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp_tunnel.h |  6 ++++++
>  include/drm/display/drm_dp_tunnel.h            |  6 ++++++
>  4 files changed, 43 insertions(+)
> 
> diff --git a/drivers/gpu/drm/display/drm_dp_tunnel.c
> b/drivers/gpu/drm/display/drm_dp_tunnel.c
> index f442430d8de7..39c07cb4123b 100644
> --- a/drivers/gpu/drm/display/drm_dp_tunnel.c
> +++ b/drivers/gpu/drm/display/drm_dp_tunnel.c
> @@ -149,6 +149,7 @@ struct drm_dp_tunnel {
>  	bool bw_alloc_enabled:1;
>  	bool has_io_error:1;
>  	bool destroyed:1;
> +	bool pr_optimization_support:1;
>  };
>  
>  struct drm_dp_tunnel_group_state;
> @@ -508,6 +509,8 @@ create_tunnel(struct drm_dp_tunnel_mgr *mgr,
>  
>  	tunnel->bw_alloc_supported =
> tunnel_reg_bw_alloc_supported(regs);
>  	tunnel->bw_alloc_enabled =
> tunnel_reg_bw_alloc_enabled(regs);
> +	tunnel->pr_optimization_support = tunnel_reg(regs,
> DP_TUNNELING_CAPABILITIES) &
> +					 
> DP_PANEL_REPLAY_OPTIMIZATION_SUPPORT;
>  
>  	if (!add_tunnel_to_group(mgr, drv_group_id, tunnel)) {
>  		kfree(tunnel);
> @@ -1036,6 +1039,20 @@ bool drm_dp_tunnel_bw_alloc_is_enabled(const
> struct drm_dp_tunnel *tunnel)
>  }
>  EXPORT_SYMBOL(drm_dp_tunnel_bw_alloc_is_enabled);
>  
> +/**
> + * drm_dp_tunnel_pr_optimization_supported - Query the PR BW
> optimization support
> + * @tunnel: Tunnel object
> + *
> + * Query if the PR BW optimization is supported for @tunnel.
> + *
> + * Returns %true if the PR BW optimiation is supported for @tunnel.
> + */
> +bool drm_dp_tunnel_pr_optimization_supported(const struct
> drm_dp_tunnel *tunnel)
> +{
> +	return tunnel && tunnel->pr_optimization_support;
> +}
> +EXPORT_SYMBOL(drm_dp_tunnel_pr_optimization_supported);
> +
>  static int clear_bw_req_state(struct drm_dp_aux *aux)
>  {
>  	u8 bw_req_mask = DP_BW_REQUEST_SUCCEEDED |
> DP_BW_REQUEST_FAILED;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> index 1fd1ac8d556d..075aea9d6ede 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> @@ -296,6 +296,20 @@ bool intel_dp_tunnel_bw_alloc_is_enabled(struct
> intel_dp *intel_dp)
>  	return drm_dp_tunnel_bw_alloc_is_enabled(intel_dp->tunnel);
>  }
>  
> +/**
> + * intel_dp_tunnel_pr_optimization_supported - Query the PR BW
> optimization support
> + * @intel_dp: DP port object
> + *
> + * Query whether a DP tunnel is connected on @intel_dp and the
> tunnel supports
> + * the PR BW optimization.

How this is checking if DP tunnel is connected? To me it looks like it
is just checking if PR BW optimization is supported.

> + *
> + * Returns %true if the BW allocation mode is supported on
> @intel_dp.
> + */
> +bool intel_dp_tunnel_pr_optimization_supported(struct intel_dp
> *intel_dp)
> +{
> +	return drm_dp_tunnel_pr_optimization_supported(intel_dp-
> >tunnel);
> +}

I would guess it is not ok to mix Intel specific and generic drm
changes into one patch.

Maybe you could add:

if (DISPLAY_VER(display) < 35)
	return false;

into here? Otherwise you need to modify check in patch 3 as:

if (intel_dp_tunnel_bw_alloc_is_enabled(intel_dp) &&
    (DISPLAY_VER(display) < 35 ||
     !intel_dp_tunnel_pr_optimization_supported(intel_dp)))
    
	   BR,
Jouni Högander

> +
>  /**
>   * intel_dp_tunnel_suspend - Suspend a DP tunnel connected on a port
>   * @intel_dp: DP port object
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> b/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> index 7f0f720e8dca..03e147736b65 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> @@ -32,6 +32,7 @@ void intel_dp_tunnel_resume(struct intel_dp
> *intel_dp,
>  void intel_dp_tunnel_suspend(struct intel_dp *intel_dp);
>  
>  bool intel_dp_tunnel_bw_alloc_is_enabled(struct intel_dp *intel_dp);
> +bool intel_dp_tunnel_pr_optimization_supported(struct intel_dp
> *intel_dp);
>  
>  void
>  intel_dp_tunnel_atomic_cleanup_inherited_state(struct
> intel_atomic_state *state);
> @@ -76,6 +77,11 @@ static inline bool
> intel_dp_tunnel_bw_alloc_is_enabled(struct intel_dp *intel_dp
>  	return false;
>  }
>  
> +static inline bool intel_dp_tunnel_pr_optimization_supported(struct
> intel_dp *intel_dp)
> +{
> +	return false;
> +}
> +
>  static inline void
>  intel_dp_tunnel_atomic_cleanup_inherited_state(struct
> intel_atomic_state *state) {}
>  
> diff --git a/include/drm/display/drm_dp_tunnel.h
> b/include/drm/display/drm_dp_tunnel.h
> index 87212c847915..4aa3ce9fd829 100644
> --- a/include/drm/display/drm_dp_tunnel.h
> +++ b/include/drm/display/drm_dp_tunnel.h
> @@ -53,6 +53,7 @@ int drm_dp_tunnel_destroy(struct drm_dp_tunnel
> *tunnel);
>  int drm_dp_tunnel_enable_bw_alloc(struct drm_dp_tunnel *tunnel);
>  int drm_dp_tunnel_disable_bw_alloc(struct drm_dp_tunnel *tunnel);
>  bool drm_dp_tunnel_bw_alloc_is_enabled(const struct drm_dp_tunnel
> *tunnel);
> +bool drm_dp_tunnel_pr_optimization_supported(const struct
> drm_dp_tunnel *tunnel);
>  int drm_dp_tunnel_alloc_bw(struct drm_dp_tunnel *tunnel, int bw);
>  int drm_dp_tunnel_get_allocated_bw(struct drm_dp_tunnel *tunnel);
>  int drm_dp_tunnel_update_state(struct drm_dp_tunnel *tunnel);
> @@ -140,6 +141,11 @@ static inline bool
> drm_dp_tunnel_bw_alloc_is_enabled(const struct drm_dp_tunnel
>  	return false;
>  }
>  
> +static inline bool drm_dp_tunnel_pr_optimization_supported(const
> struct drm_dp_tunnel *tunnel)
> +{
> +	return false;
> +}
> +
>  static inline int
>  drm_dp_tunnel_alloc_bw(struct drm_dp_tunnel *tunnel, int bw)
>  {