Re: [Intel-gfx] [PATCH v3] drm/i915/hdcp: Update CP as per the kernel internal state

[Ramalingam C <ramalingam.c@intel.com>]

On 2020-06-30 at 13:50:48 +0530, Anshuman Gupta wrote:
> Content Protection property should be updated as per the kernel
> internal state. Let's say if Content protection is disabled
> by userspace, CP property should be set to UNDESIRED so that
> reauthentication will not happen until userspace request it again,
> but when kernel disables the HDCP due to any DDI disabling sequences
> like modeset/DPMS operation, kernel should set the property to
> DESIRED, so that when opportunity arises, kernel will start the
> HDCP authentication on its own.
> 
> Somewhere in the line, state machine to set content protection to
> DESIRED from kernel was broken and IGT coverage was missing for it.
> This patch fixes it.
> 
> v2:
> - Fixing hdcp CP state in connector atomic check function
>   intel_hdcp_atomic_check(). [Maarten]
>   This will require to check hdcp->value in intel_hdcp_update_pipe()
>   in order to avoid enabling hdcp, if it was already enabled.
> 
> v3:
> - Rebased.
> 
> Cc: Ramalingam C <ramalingam.c@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Reviewed-by: Uma Shankar <uma.shankar@intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> Link: https://patchwork.freedesktop.org/patch/350962/?series=72664&rev=2 #v1
> Link: https://patchwork.freedesktop.org/patch/359396/?series=72251&rev=3 #v2
> ---
>  drivers/gpu/drm/i915/display/intel_hdcp.c | 27 +++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index 815b054bb167..0d410652e194 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -2086,6 +2086,7 @@ void intel_hdcp_update_pipe(struct intel_atomic_state *state,
>  		(conn_state->hdcp_content_type != hdcp->content_type &&
>  		 conn_state->content_protection !=
>  		 DRM_MODE_CONTENT_PROTECTION_UNDESIRED);
> +	bool desired_and_not_enabled = false;
>  
>  	/*
>  	 * During the HDCP encryption session if Type change is requested,
> @@ -2108,8 +2109,15 @@ void intel_hdcp_update_pipe(struct intel_atomic_state *state,
>  	}
>  
>  	if (conn_state->content_protection ==
> -	    DRM_MODE_CONTENT_PROTECTION_DESIRED ||
> -	    content_protection_type_changed)
> +	    DRM_MODE_CONTENT_PROTECTION_DESIRED) {
> +		mutex_lock(&hdcp->mutex);
> +		/* Avoid enabling hdcp, if it already ENABLED */
> +		desired_and_not_enabled =
> +			hdcp->value != DRM_MODE_CONTENT_PROTECTION_ENABLED;

It will be good to move before the hdcp->value modification as below,
if (content_protection_type_changed)
	hdcp->value = DRM_MODE_CONTENT_PROTECTION_DESIRED;

But this will impact only when content_protection_type_changed is true.
But when content_protection_type_changed is true we dont care the state of
desired_and_not_enabled as we use them in logical OR.

Either way. looks good to me.

Reviewed-by: Ramalingam C <ramalingam.c@intel.com>

> +		mutex_unlock(&hdcp->mutex);
> +	}
> +
> +	if (desired_and_not_enabled || content_protection_type_changed)
>  		intel_hdcp_enable(connector,
>  				  crtc_state->cpu_transcoder,
>  				  (u8)conn_state->hdcp_content_type);
> @@ -2158,6 +2166,19 @@ void intel_hdcp_atomic_check(struct drm_connector *connector,
>  		return;
>  	}
>  
> +	crtc_state = drm_atomic_get_new_crtc_state(new_state->state,
> +						   new_state->crtc);
> +	/*
> +	 * Fix the HDCP uapi content protection state in case of modeset.
> +	 * FIXME: As per HDCP content protection property uapi doc, an uevent()
> +	 * need to be sent if there is transition from ENABLED->DESIRED.
> +	 */
> +	if (drm_atomic_crtc_needs_modeset(crtc_state) &&
Based on the IGT test result I infer needs_modeset status wont change from No->yes
after this point.

-ram
> +	    (old_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED &&
> +	    new_cp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED))
> +		new_state->content_protection =
> +			DRM_MODE_CONTENT_PROTECTION_DESIRED;
> +
>  	/*
>  	 * Nothing to do if the state didn't change, or HDCP was activated since
>  	 * the last commit. And also no change in hdcp content type.
> @@ -2170,8 +2191,6 @@ void intel_hdcp_atomic_check(struct drm_connector *connector,
>  			return;
>  	}
>  
> -	crtc_state = drm_atomic_get_new_crtc_state(new_state->state,
> -						   new_state->crtc);
>  	crtc_state->mode_changed = true;
>  }
>  
> -- 
> 2.26.2
> 
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