Re: [Intel-gfx] [PATCH v5 03/10] drm/hdcp: Update property value on content type and user changes

[Sean Paul <sean@poorly.run>]

On Tue, Apr 12, 2022 at 09:25:59AM -0400, Rodrigo Vivi wrote:
> On Mon, Apr 11, 2022 at 08:47:32PM +0000, Sean Paul wrote:
> > From: Sean Paul <seanpaul@chromium.org>
> > 
> > This patch updates the connector's property value in 2 cases which were
> > previously missed:
> > 
> > 1- Content type changes. The value should revert back to DESIRED from
> >    ENABLED in case the driver must re-authenticate the link due to the
> >    new content type.
> > 
> > 2- Userspace sets value to DESIRED while ENABLED. In this case, the
> >    value should be reset immediately to ENABLED since the link is
> >    actively being encrypted.
> > 
> > To accommodate these changes, I've split up the conditionals to make
> > things a bit more clear (as much as one can with this mess of state).
> > 
> > Acked-by: Jani Nikula <jani.nikula@intel.com>
> > Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
> > Signed-off-by: Sean Paul <seanpaul@chromium.org>
> > Link: https://patchwork.freedesktop.org/patch/msgid/20210913175747.47456-4-sean@poorly.run #v1
> > Link: https://patchwork.freedesktop.org/patch/msgid/20210915203834.1439-4-sean@poorly.run #v2
> > Link: https://patchwork.freedesktop.org/patch/msgid/20211001151145.55916-4-sean@poorly.run #v3
> > Link: https://patchwork.freedesktop.org/patch/msgid/20211105030434.2828845-4-sean@poorly.run #v4
> > 
> > Changes in v2:
> > -None
> > Changes in v3:
> > -Fixed indentation issue identified by 0-day
> > Changes in v4:
> > -None
> > Changes in v5:
> > -None
> > ---
> >  drivers/gpu/drm/drm_hdcp.c | 26 +++++++++++++++++---------
> >  1 file changed, 17 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c
> > index dd8fa91c51d6..8c851d40cd45 100644
> > --- a/drivers/gpu/drm/drm_hdcp.c
> > +++ b/drivers/gpu/drm/drm_hdcp.c
> > @@ -487,21 +487,29 @@ bool drm_hdcp_atomic_check(struct drm_connector *connector,
> >  		return true;
> >  
> >  	/*
> > -	 * Nothing to do if content type is unchanged and one of:
> > -	 *  - state didn't change
> > +	 * Content type changes require an HDCP disable/enable cycle.
> > +	 */
> > +	if (new_conn_state->hdcp_content_type != old_conn_state->hdcp_content_type) {
> 
> shouldn't we add some && ( old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED)) {
> here?

Thanks for your reviews Rodrigo.

I don't think so since the content type is changing the current state of old
content protection is immaterial (ie: if we need to enable HDCP 2.x, the state
of HDCP 1.x doesn't really matter), we need to re-evaluate whether the current
level of HDCP is sufficient.

Hopefully that makes sense, but I could be missing something :-)

Sean

> 
> > +		new_conn_state->content_protection =
> > +			DRM_MODE_CONTENT_PROTECTION_DESIRED;
> > +		return true;
> > +	}
> > +
> > +	/*
> > +	 * Ignore meaningless state changes:
> >  	 *  - HDCP was activated since the last commit
> > -	 *  - attempting to set to desired while already enabled
> > +	 *  - Attempting to set to desired while already enabled
> >  	 */
> > -	if (old_hdcp == new_hdcp ||
> > -	    (old_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED &&
> > +	if ((old_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED &&
> >  	     new_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED) ||
> >  	    (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED &&
> >  	     new_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED)) {
> > -		if (old_conn_state->hdcp_content_type ==
> > -				new_conn_state->hdcp_content_type)
> > -			return false;
> > +		new_conn_state->content_protection =
> > +			DRM_MODE_CONTENT_PROTECTION_ENABLED;
> > +		return false;
> >  	}
> >  
> > -	return true;
> > +	/* Finally, if state changes, we need action */
> > +	return old_hdcp != new_hdcp;
> >  }
> >  EXPORT_SYMBOL(drm_hdcp_atomic_check);
> > -- 
> > Sean Paul, Software Engineer, Google / Chromium OS
> > 

-- 
Sean Paul, Software Engineer, Google / Chromium OS