Re: [Intel-gfx] [PATCH 1/4] drm/i915/hdcp: Update CP as per the kernel internal state

[Anshuman Gupta <anshuman.gupta@intel.com>]

On 2020-03-03 at 15:36:37 +0100, Maarten Lankhorst wrote:
> Op 05-02-2020 om 06:07 schreef Anshuman Gupta:
> > On 2020-01-28 at 21:45:45 +0530, Anshuman Gupta wrote:
> > Hi Jani ,
> > As per my understanding intel_hdcp_atomic_check() is not sufficient to
> > fix the broken hdcp uapi state, as the state fixup required in case
> > of modeset.
> > If you do not have any concern, can we continue with the patch.
> > Thanks,
> > Anshuman Gupta.
> 
> Hey,
>
Thanks martin for review. 
As full modeset DDI disable sequence  (encoder->disable()->intel_hdcp_disable()) can cause HDCP to 
disable without user space knowledge i.e. when Content Protetion state is not UNDESIRED, in those cases
we want to fix the HDCP Content Protection state.  
> In case of a modeset, don't we always call atomic_check() on the connector, either before or after?
yes it calls drm_atomic_helper_check_modeset()->intel_digital_connector_atomic_check()->intel_hdcp_atomic_check(),
but if we fix HDCP state in intel_hdcp_atomic_check(), there may be a case at later point that fastset 
check is true, which disable need_modeset and enable update_pipe due to which encoder->update_pipe()->intel_hdcp_update_pipe()
may endup enabling HDCP again when HDCP is already enabled, which is wrong.
> 
> Should be fine to fixup there then?
Therefore we want to fixup the HDCP state only when full modeset is required, when it is going
to disable DDI.

Thanks ,
Anshuman Gupta.
> 
> >> On 2020-01-28 at 21:14:44 +0530, Anshuman Gupta wrote:
> >>> On 2020-01-28 at 16:19:31 +0200, Jani Nikula wrote:
> >>>> On Tue, 28 Jan 2020, Anshuman Gupta <anshuman.gupta@intel.com> 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.
> >>>>> IGT patch to catch further regression on this features is being
> >>>>> worked upon.
> >>>>>
> >>>>> CC: Ramalingam C <ramalingam.c@intel.com>
> >>>>> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> >>>>> ---
> >>>>>  drivers/gpu/drm/i915/display/intel_display.c |  4 +++
> >>>>>  drivers/gpu/drm/i915/display/intel_hdcp.c    | 26 ++++++++++++++++++++
> >>>>>  drivers/gpu/drm/i915/display/intel_hdcp.h    |  2 ++
> >>>>>  3 files changed, 32 insertions(+)
> >>>>>
> >>>>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> >>>>> index da5266e76738..934cdf1f1858 100644
> >>>>> --- a/drivers/gpu/drm/i915/display/intel_display.c
> >>>>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> >>>>> @@ -14595,6 +14595,10 @@ static int intel_atomic_check(struct drm_device *dev,
> >>>>>  		goto fail;
> >>>>>  
> >>>>>  	if (any_ms) {
> >>>>> +		/*
> >>>>> +		 * When there is modeset fix the hdcp uapi CP state.
> >>>>> +		 */
> >>>>> +		intel_hdcp_post_need_modeset_check(state);
> >>>>>  		ret = intel_modeset_checks(state);
> >>>>>  		if (ret)
> >>>>>  			goto fail;
> >>>>> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> >>>>> index 0fdbd39f6641..be083136eee2 100644
> >>>>> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> >>>>> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> >>>>> @@ -2074,6 +2074,32 @@ void intel_hdcp_atomic_check(struct drm_connector *connector,
> >>>>>  	crtc_state->mode_changed = true;
> >>>>>  }
> >>>>>  
> >>>>> +/**
> >>>>> + * intel_hdcp_post_need_modeset_check.
> >>>>> + * @state: intel atomic state.
> >>>>> + *
> >>>>> + * This function fix the HDCP uapi state when hdcp disabling initiated from
> >>>>> + * modeset DDI disabling sequence. It updates uapi CP state from ENABLED to
> >>>>> + * DESIRED so that HDCP uapi state can be restored as per HDCP Auth state.
> >>>>> + * This function should be called only in case of 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.
> >>>>> + */
> >>>>> +void intel_hdcp_post_need_modeset_check(struct intel_atomic_state *state)
> >>>>> +{
> >>>>> +	struct drm_connector *connector;
> >>>>> +	struct drm_connector_state *old_state;
> >>>>> +	struct drm_connector_state *new_state;
> >>>>> +	int i;
> >>>>> +
> >>>>> +	for_each_oldnew_connector_in_state(&state->base, connector, old_state,
> >>>>> +					   new_state, i) {
> >>>>> +		if (old_state->content_protection == DRM_MODE_CONTENT_PROTECTION_ENABLED &&
> >>>>> +		    new_state->content_protection != DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
> >>>>> +			new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
> >>>>> +	}
> >>>>> +}
> >>>>> +
> >>>> Why does this feel like duplication of what you already have in
> >>>> intel_hdcp_atomic_check()?
> >>> intel_hdcp_atomic_check() have checks that for disconnected connector and it doesn't look for 
> >> typo here, "intel_hdcp_atomic_check() checks that for disconnected connector and it doesn't check for new state shouldn't be UNDESIRED" 
> >>> old state, that is not sufficient to fix the hdcp CP uapi state, it need to be fix only in case of
> >>> modeset, Later on a fastset check can disable the modeset and we would endup calling intel_hdcp_enable
> >>> while hdcp is already enabled. That is the reason i think we would require a new API to
> >>> fix the uapi state.
> >>> Thanks ,
> >>> Anshuman Gupta.
> >>>> BR,
> >>>> Jani.
> >>>>
> >>>>
> >>>>>  /* Handles the CP_IRQ raised from the DP HDCP sink */
> >>>>>  void intel_hdcp_handle_cp_irq(struct intel_connector *connector)
> >>>>>  {
> >>>>> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.h b/drivers/gpu/drm/i915/display/intel_hdcp.h
> >>>>> index f3c3272e712a..7bf46bc3c348 100644
> >>>>> --- a/drivers/gpu/drm/i915/display/intel_hdcp.h
> >>>>> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.h
> >>>>> @@ -13,6 +13,7 @@
> >>>>>  struct drm_connector;
> >>>>>  struct drm_connector_state;
> >>>>>  struct drm_i915_private;
> >>>>> +struct intel_atomic_state;
> >>>>>  struct intel_connector;
> >>>>>  struct intel_hdcp_shim;
> >>>>>  enum port;
> >>>>> @@ -21,6 +22,7 @@ enum transcoder;
> >>>>>  void intel_hdcp_atomic_check(struct drm_connector *connector,
> >>>>>  			     struct drm_connector_state *old_state,
> >>>>>  			     struct drm_connector_state *new_state);
> >>>>> +void intel_hdcp_post_need_modeset_check(struct intel_atomic_state *state);
> >>>>>  int intel_hdcp_init(struct intel_connector *connector,
> >>>>>  		    const struct intel_hdcp_shim *hdcp_shim);
> >>>>>  int intel_hdcp_enable(struct intel_connector *connector,
> >>>> -- 
> >>>> Jani Nikula, Intel Open Source Graphics Center
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >
> 
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